
457 S.E.2d 881 (1995)
119 N.C. App. 169
Terry Lee TEDDER
v.
Robert F. HODGES, Commissioner, North Carolina Division of Motor Vehicles.
No. COA94-824.
Court of Appeals of North Carolina.
June 6, 1995.
*883 Morrow Alexander Tash & Long by C.R. "Skip" Long, Jr., Winston-Salem, for petitioner-appellant.
Atty. Gen. Michael F. Easley by Assoc. Atty. Gen. C. Norman Young, for respondent-appellee.
EAGLES, Judge.

I.
Petitioner argues that the trial court erred in its refusal to consider or admit the expert opinion testimony of Dr. Alford. Respondent responds that petitioner has failed to preserve this assignment of error for appellate review.
For a party to preserve for appellate review the exclusion of evidence, "the significance of the excluded evidence must be made to appear in the record and a specific offer of proof is required unless the significance of the evidence is obvious from the record." *884 State v. Simpson, 314 N.C. 359, 370, 334 S.E.2d 53, 60 (1985). See also River Hills Country Club v. Queen City, 95 N.C.App. 442, 446, 382 S.E.2d 849, 851 (1989). Here, when petitioner moved to introduce Dr. Alford's deposition into evidence, respondent objected to its admission. Petitioner's counsel then told the trial court what Dr. Alford's deposition testimony would show, but the trial court ruled that it would not consider any of Dr. Alford's testimony. Respondent argues that the summary of Dr. Alford's testimony was not an offer of proof and was not sufficient to preserve petitioner's assignment of error for appellate review. After reviewing the record, we conclude that the summary of Dr. Alford's testimony given by petitioner's counsel was sufficient to clearly show us what the excluded evidence would have revealed. Accordingly, we conclude that petitioner has preserved the issue of the exclusion of Dr. Alford's testimony for appellate review and we now address the merits of this assignment of error.
Petitioner argues that Dr. Alford's testimony was admissible and that the trial court erred in excluding it based solely on the fact that Dr. Alford had not personally examined petitioner. Respondent conceded at trial that Dr. Alford would qualify as an expert witness. The test for admissibility of the opinion of an expert witness is helpfulness to the trier of fact and the trial court's decision on admissibility will be reversed only for an abuse of discretion. Jennings v. Jessen, 103 N.C.App. 739, 745, 407 S.E.2d 264, 267-68 (1991). In appropriate situations, "an expert can base opinion testimony on other than first-hand knowledge." Guyther v. Nationwide Mut. Fire Ins. Co., 109 N.C.App. 506, 516, 428 S.E.2d 238, 243 (1993). After reviewing the record, we conclude that Dr. Alford's testimony would not have been helpful to the trier of fact because it would not have helped to show whether or not petitioner willfully refused to breathe into the machine on 29 May 1994. Accordingly, the trial court did not err in excluding Dr. Alford's deposition testimony.

II.
Petitioner also argues that the trial court erred in refusing to enter judgment in favor of petitioner at the end of respondent's evidence. Pursuant to G.S. 20-16.2(d), a driver whose license has been revoked for committing an implied-consent offense may request a hearing to determine whether:
(1) The person was charged with an implied-consent offense;
(2) The charging officer had reasonable grounds to believe that the person had committed an implied-consent offense;
(3) The implied-consent offense charged involved death or critical injury to another person, if this allegation is in the affidavit;
(4) The person was notified of his rights as required by subsection (a); and
(5) The person willfully refused to submit to a chemical analysis upon the request of the charging officer.
G.S. 20-16.2(e) provides that "[i]f the revocation is sustained after the hearing, the person whose license has been revoked has the right to file a petition in the superior court for a hearing de novo upon the issues listed in subsection (d)."
Petitioner argues that the trial court erred in failing to enter judgment in favor of petitioner at the end of respondent's evidence because respondent's evidence failed to prove that petitioner willfully refused to submit to the chemical analysis. When a trial judge sits as the trier of fact, his findings of fact and conclusions of law are conclusive on appeal if supported by competent evidence. General Specialities Co. v. Nello L. Teer Co., 41 N.C.App. 273, 275, 254 S.E.2d 658, 660 (1979). "This is true even though there may be evidence in the record to the contrary which could sustain findings to the contrary." Id.
Here, Officer Kapps testified that after Officer Hutchins requested petitioner to take a breathalyzer test, petitioner put his fingers in his mouth and Officer Kapps had to restart the observation. Officer Kapps admitted that she had not told petitioner not to put anything in his mouth, but after he put his fingers in his mouth, she instructed him that if he did it again, he would be written up as a refusal. Officer Kapps further testified that after the second observation period, petitioner *885 blew into the instrument five or six times, but that "when he got the tone to start, he would stop blowing." Officer Kapps testified that she told petitioner before he started blowing that she "needed for him to blow hard enough to bring that tone on and to blow until [she] told him to stop." Officer Kapps testified that she could not tell if petitioner physically could not blow into the machine or if he was intentionally not blowing. Although Officer Hutchins testified that petitioner appeared to be generally cooperative, Officer Hutchins also testified that petitioner "kept leaning over and putting his fingers in his mouth" and that Officer Kapps and he had to tell petitioner several times not to put his fingers in his mouth or they would write him up as a refusal.
Petitioner points to our Supreme Court's decision in Etheridge v. Peters, 301 N.C. 76, 81, 269 S.E.2d 133, 136 (1980) where the Court stated:
[A] willful refusal to submit to a chemical test within the meaning of G.S. 20-16.2(c) occurs where a motorist: (1) is aware that he has a choice to take or to refuse to take the test; (2) is aware of the time limit within which he must take the test; (3) voluntarily elects not to take the test; and (4) knowingly permits the prescribed thirty-minute time limit to expire before he elects to take the test.
Petitioner argues that respondent did not satisfy the third element of the Peters test because respondent's evidence showed that petitioner voluntarily elected to take the test. We disagree. After reviewing the record, we conclude that respondent's evidence showed that petitioner failed to follow the instructions of the breathalyzer operator, Officer Kapps. Failure to follow the instructions of the breathalyzer operator is an adequate basis for the trial court to conclude that petitioner willfully refused to submit to a chemical analysis. Bell v. Powell, 41 N.C.App. 131, 135, 254 S.E.2d 191, 194 (1979). Accordingly, the trial court properly declined to enter judgment in favor of petitioner at the end of respondent's evidence.

III.
Petitioner also argues that the trial court erred in its refusal to enter judgment in favor of petitioner at the end of all the evidence because respondent failed to establish that petitioner willfully refused to take the breathalyzer test. After respondent presented its evidence, petitioner testified that although the officers thought he was intentionally putting his fingers in his mouth, he was actually biting his nails out of nervousness. Petitioner also testified that he suffers from bronchitis and that he could not blow into the machine on the night in question because of his bronchitis and because his nose had been injured during a fight on that date. He insisted that he tried to blow because he knew he would lose his license and would lose his job if he was written up as a refusal.
While this evidence could have led the trial court to determine that petitioner did not willfully refuse to blow into the breathalyzer machine, we conclude that there was still competent evidence to support the trial court's conclusion that petitioner willfully refused. When the trial judge is the trier of fact, "he has the duty to pass upon the credibility of the witnesses who testify. He decides what weight shall be given to the testimony and the reasonable inferences to be drawn therefrom. The appellate court cannot substitute itself for the trial judge in this task." Nello L. Teer Co. at 275, 254 S.E.2d at 660. Accordingly, this assignment of error fails.

IV.
Petitioner argues that the trial court erred in its failure to make any findings of fact to resolve why petitioner was unable to give a sufficient breath sample. G.S. 1A-1, Rule 52(a)(1) provides that in a non-jury trial, the trial court must "find the facts specially and state separately its conclusions of law thereon and direct the entry of the appropriate judgment." "However, the trial court need not recite every evidentiary fact presented at the hearing, but must only make specific findings on the ultimate facts established by the evidence that are determinative of the questions raised in the action *886 and essential to support its conclusions." Tolbert v. Hiatt, 95 N.C.App. 380, 385, 382 S.E.2d 453, 456 (1989). In its judgment, the trial court found inter alia:
6. The breathalyzer operator first began observing petitioner at 10:47 p.m. Petitioner was informed of his rights regarding chemical analysis pursuant to G.S. 20-16.2 at 10:47 p.m. Petitioner indicated that he would submit to a chemical analysis of his breath.
7. Thereafter, petitioner blew into the machine five or six times but failed to give a sufficient sample for analysis each time. Petitioner was thereafter informed that he was being written up as having refused the test.
Petitioner contends that the trial court's seventh finding of fact was not an ultimate fact and was insufficient to indicate that the trial court rejected petitioner's argument that his inability to give a breath sample was not willful or was excusable under the circumstances. We disagree. Here, the trial court made findings that petitioner was informed of his rights regarding chemical analysis, petitioner indicated he would submit to the test, and petitioner blew into the machine five or six times but failed to give a sufficient sample for analysis. The purpose of requiring sufficient findings of fact is to allow "meaningful appellate review." Hiatt at 385, 382 S.E.2d at 456. The findings here were sufficient to allow us to determine whether the trial court's judgment and legal conclusions were a correct application of the law. Accordingly, petitioner's assignment of error fails.

V.
Petitioner also argues that the trial court's conclusion of law that petitioner willfully refused to submit to a chemical analysis is not supported by any findings of fact and is contrary to the evidence. We have already addressed this assignment of error in II. and III., supra, and we have concluded that the trial court's conclusion of law regarding petitioner's willful refusal is supported by adequate findings and by competent evidence in the record.

VI.
Finally, petitioner argues that the trial court erred in affirming the revocation order because it is not supported by proper findings, conclusions, and is an abuse of discretion. We have addressed the merits of this argument, supra, and we have concluded that this assignment of error fails.
Affirmed.
JOHN C. MARTIN and WALKER, JJ., concur.
