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 $$350$ in Allowance for Doubtful Accounts just prior to adjustment. Using the aging method, the balance of Allowance for Doubtrul Accounts is estimated as $$7,870.$

Amount added

Ending balance

b$.$ Credit balance of $$350$ in Allowance for Doubtful Accounts just prior to adjustment. Bad debt expense is estimated at $2\%$ of credit sales, which totaled $$983,000$ for the year.

Amount added

Ending balance

$