Answer and Explanation:
The journal entries are shown below;
Allowance for doubtful accounts $1,900
To Accounts receivable—C. Green $1,900
(being the written off amount is recorded)
Accounts receivable—C. Green $1,400
To Allowance for doubtful accounts $1,400
(being the previously written off is recorded)
Cash Dr $1,400
To Account receivable $1,400
(Being the payment is recorded)