I am confused on these problems. Please help.

The leadger of Elburn Company at the end of the current year shows Account Receivable $110,000, Sales $840,000, and Sales Returns and Allowances $28,000.

A) If Elburn uses the direct write-off method to account for uncollectible accounts, journalize the adjusting entry at Dec. 31, assuming Elburn determines that Copp's $1,400 balance is uncollectible.

B)If Allowance for Doubtful Account has a credit balance of $2,100 in the trial balance, journalize the adjusting entry at Dec. 31, assuming bad debts are expected to be (1) 1% of net sales, and (2) 10% of accounts receivable.

C) If Allowance for Doubtful Accounts has a debit balance of $200 in the trial balance, journalize the adjusting entry at Dec. 31, assuming bad debts are expected to be (1) 0.75% of net sales and (2) 6% of accounts receivable.