135. Determine the amount to be aded to Allowance for Doublful Accounts in each nf the following cases and indicate the ending balance in each case. (a) Credit balance of $300 in Allowance for Doubtful Accounts just prior to adjustment. Analysis of Accounts Receivable indicates uncollectible receivables of $8,500. (b) Credit balance of $500 in Allowance for Doubtful Accounts just prior to adjustment. Uncollectible receivables are estimated at 2% of credit sales, which totaled $1,000,000 for the year