Answer:
a. 
Date       Account Title                                                      Debit              Credit
Dec, 31   Bad debt expense                                          $15,700
               Allowance for doubtful expense account                            $15,700
<u>Working</u>
= 5% * 314,000
= $15,700
b. 
Date       Account Title                                                      Debit              Credit
Dec, 31   Bad debt expense                                          $36,840
               Allowance for doubtful expense account                            $36,840
<u>Working </u>
= 3% * (Cash sales + Credit sales)
= 3% * (914,000 + 314,000)
= $36,840
c. 
Date       Account Title                                                      Debit              Credit
Dec, 31   Bad debt expense                                          $17,520
               Allowance for doubtful expense account                            $17,520
<u>Working</u>
= (8% * Year end accounts receivable) + Debit balance for Allowance for doubtful account
= (8% * 139,000) + 6,400
= $17,520