Answer:
The debit to bad debts expense for 2015 would be: $4,100
Explanation:
Z Company uses the accounts receivable aging method to estimates uncollectible and the amount of estimated uncollectible for 2015 was $4,000.
The balance in the allowance account at January 1, 2015 was a $300 credit and Z Co. wrote off $400 of accounts receivable during the year.
Therefore, before adjusment, on 31 December 2015, the balance in the allowance account was a $100 debit.
Bad debts expense for 2015 = $4,000 + $100 = $4,100
