help with uncollectable accounts!

Crell Computers categorizes its accounts recelvable into four age groups for purposes of estimating its allowance for uncollectible accounts. 1. Accounts not yet due =$48,000; estimated uncollectible =7%. 2. Accounts 130 days past due =$12,100; estimated uncollectible =9%, 3. Accounts 3160 days past due =$8,100; estimated uncollectible =17%. 4. Accounts more than 60 days past due =$4,100; estimated uncollectible =25%. What should be the balance in Crell's allowance for uncollectible accounts