a company recorded credit sales of $764,000, of which $540,000 is not yet due, $150,000 is past due for up to 180 days, and $74,000 is past due for more than 180 days. under the aging of receivables method, the company expects it will not collect 6% of the amount not yet due, 15% of the amount past due for up to 180 days, and 28% of the amount past due for more than 180 days. the allowance account had a debit balance of $4,200 before adjustment. after adjusting for bad debt expense, what is the ending balance of the allowance account?