account_correction

The mistake made in the question:
DR Prepayment (B/S) $1700
CR Salaries (P/L) $1700
So,
(1) REVERSE the entry made in order to setoff it by:
DR Salaries (P/L) $1700
CR Prepayment (B/S) $1700
(2) made a correct entry for the transaction by:
DR Salaries (P/L) $1700
CR Accrual (B/S) $1700
As a result, the adjustment is as stated:
DR Salaries (P/L) $3400
CR Accrual (B/S) $1700
CR Prepayment (B/S) $1700


In Balance Sheet:
Accrual 應付而未付 = 記錄該年度應該付之款項(如3月份薪金),卻未能於該年度年結前(如3月31日)付款,視之為"Accrual",DR Salaries & CR Accrual. 如到了4月9日付款,DR Accrual & CR Bank.

Prepayment 預付款 = 記錄該年度已付款之費用(如3月已預早支付了4月份租金),實為下年度之支出項目(4月份租金),視之為"Prepayment", DR Prepayment & CR Bank. 到了4月1日新年度, DR Rental Expense & CR Prepayment.

當初Accrual salaries of $1700. had been wrongly accounted for as an prepayment時，其transation voucher as:
Dr prepayment 1700
Cr salaries 1700
現發現錯誤，首先要沖銷上述voucher:
Dr salaries 1700
Cr prepayment 1700
然後入番正確的voucher:
Dr salaries 1700
Cr accural salaries 1700
綜合上述兩條，得出
Dr salaries 3400
Cr prepayment 1700
Cr accural salaries 1700