Concord Corporation uses the percentage-of-receivables basis to record bad debt expense and concludes that 4% of accounts receivable will become uncollectible. Accounts receivable are $421,300 at the end of the year, and the allowance for doubtful accounts has a credit balance of $2,921. (a) Prepare the adjusting journal entry to record bad debt expense for the year. (b) If the allowance for doubtful accounts had a debit balance of $870 instead of a credit balance of $2,921, prepare the adjusting journal entry for bad debt expense. (Credit account titles are automatically indented when amount is entered. Do not indent manually.)