Determine the amount to be added to Allowance for Doubtful Accounts in each of the following cases and indicate the ending balance in each case. a. Credit balance of $390 in Allowance for Doubtful Accounts just prior to adjustment. Using the aging method, the balance of Allowance for Doubtful Accounts is estimated as $7,530. Line Item Description Amount Amount added $fill in the blank 1 7,140 Ending balance $fill in the blank 2 7,530 b. Credit balance of $390 in Allowance for Doubtful Accounts just prior to adjustment. Bad debt expense is estimated at 2% of credit sales, which totaled $939,000 for the year. Line Item Description Amount Amount added $fill in the blank 3 Ending balance $fill in the blank 4