At the end of the current year, the accounts receivable account has a debit balance of $688,000 and sales for the year total $7,800,000. The allowance account before adjustment has a debit balance of $9,300. Bad debt expense is estimated at 3/4 of 1% of sales. The allowance account before adjustment has a debit balance of $9,300. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $29,800. The allowance account before adjustment has a credit balance of $6,200. Bad debt expense is estimated at 1/4 of 1% of sales. The allowance account before adjustment has a credit balance of $6,200. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $51,500. Determine the amount of the adjusting entry to provide for doubtful accounts under each of the assumptions (a through d) listed above. a. $fill in the blank 1 b. $fill in the blank 2 c. $fill in the blank 3 d. $fill in the blank 4