$3$ The ledger of Costello Company at the end of the current year shows Accounts Receivable $$110,000,$ Sales Revenue $$840,000,$ and Sales Returns and Allowances $$20,000.$Instructions$($a$)$ If Costello uses the direct write$-$off method to account for uncollectible accounts, jour$-$ nalize the adjusting entry at December $31,$ assuming Costello determines that L$.$ Doles $$1,400$ balance is uncollectible.$($b$)$ If Allowance for Doubtful Accounts has a credit balance of $$2,100$ in the trial balance, journalize the adjusting entry at December $31,$ assuming bad debts are expected to be $(1)1\%$ of net sales, and $(2)10\%$ of accounts receivable.$($c$)$ If Allowance for Doubtful Accounts has a debit balance of $$200$ in the trial balance, journalize the adjusting entry at December $31,$ assuming bad debts are expected to be $(1)0\mathrm{.}75\%$ of net sales and $(2)6\%$ of accounts receivable