a.

Solution approach: The bad debt expense recognized during the year can be determined by comparing the bad debt write-offs during the year to the change in the balance of the allowance account from the beginning to the end of the year (before considering the year-end adjustment).  Since the allowance account balance increased during the year, there was more bad debt expense recognized than accounts written-off during the year.

Bad debt expense = $23,900 - $9,720 + $10,480 = $24,660