Can some one explain these 2 to me? I'm getting stuck on calculating the balances.

Allowance for Doubtful Accounts has a credit balance of $2,100 at the end of the year (before adjustment), and an analysis of customers' accounts indicates uncollectible receivables of $19,700. Which of the following entries records the proper adjustment for bad debt expense? 0 debit Allowance for Doubtful Accounts, $17,600; credit Bad Debt Expense, $17,600 0 debit Allowance for Doubtful Accounts, $21,800; credit Bad Debt Expense, $21,800 0 debit Bad Debt Expense, $21,800; credit Allowance for Doubtful Accounts, $21,800 (9 debit Bad Debt Expense, $17,600; credit Allowance for Doubtful Accounts, $17,500 Allowance for Doubtful Accounts has a debit balance of $1,100 at the end of the year (before adjustment), and an analysis of customers' accounts indicates uncollectible receivables of $12,900. Which of the following entries records the proper adjustment for bad debt expense? (9 debit Bad Debt Expense, $14,000; credit Allowance for Doubtful Accounts, $14,000 0 debit Allowance for Doubtful Accounts, $14,000; credit Bad Debt Expense, $14,000 0 debit Allowance for Doubtful Accounts, $11,800; credit Bad Debt Expense, $11,800 0 debit Bad Debt Expense, $11,800; credit Allowance for Doubtful Accounts, $11,800 Abbott Company uses the allowance method of accounting for uncollectible accounts. Abbott estimates that 3% of net credit sales will be uncollectible. 0n Ianuary 1, the Allowance for Doubtful Accounts had a credit balance of $2,400. During the year, Abbott wrote off accounts receivable totaling $1,800 and made credit sales of $100,000. There were no sales returns or sales discounts during the year. After the adjusting entry, the December 3] balance in the Bad Debt Expense will be Your