Please, help with providing for doubtful accounts

At the end of the current year, the accounts receivable account has a debit balance of $673,000 and sales for the year total $7,630,000. a. The allowance account before adjustment has a debit balance of $9,100. Bad debt expense is estimated at 1/2 of 1% of sales. b. The allowance account before adjustment has a debit balance of $9,100. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $29,100. c. The allowance account before adjustment has a credit balance of $7,500. Bad debt expense is estimated at 3/4 of 1% of sales. d. The allowance account before adjustment has a credit balance of $7,500. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $62,300. Determine the amount of the adjusting entry to provide for doubtful accounts under each of the assumptions (a through d) listed above