Providing for Doubtful Accounts

At the end of the current year, the accounts receivable account has a debit balance of $$2,700,000$ and sales for the year total $$32,400,000.$

a$.$ The allowance account before adjustment has a debit balance of $$27,100.$ Bad debt expense is estimated at $\frac{1}{2}$ of $1\%$ of sales.

c$.$ The allowance account before adjustment has a credit balance of $$17,900.$ Bad debt expense is estimated at $\frac{3}{4}$ of $1\%$ of sales.

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$.$ $