Providing for doubtful accounts

At the end of the current year, the accounts receivable account has a debit balance of $$977,000$ and sales for the year total $$11,070,000.$

a$.$ The allowance account before adjustment has a debit balance of $$13,200.$ Bad debt expense is estimated at $\frac{1}{2}$ of $1\%$ of sales.

b$.$ The allowance account before adjustment has a debit balance of $$13,200.$ An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $$42,200.$

c$.$ The allowance account before adjustment has a credit balance of $$9,100.$ Bad debt expense is estimated at $\frac{1}{4}$ of $1\%$ of sales.

d$.$ The allowance account before adjustment has a credit balance of $$9,100.$ An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $$75,500.$

Determine the amount of the adjusting entry to provide for doubtful accounts under each of the assumptions $($a through d$)$ listed above.

a$.$ $ $$

b$.$ $

c$.$ $

d$.$ $