In order to correct this mistake you will need to adjust the Salaries Payable and Wages Expense accounts.
The bookkeeper incorrectly recorded the salary as an expense to the current period. In order to do it correctly she should have paid the balance on the Salaries Payable for $700, and then recorded the the remaining $1,800 as Wages Expense for the currently period.
The journal entry to correct this mistake is to debit Salaries Payable for $700 and credit Wages Expense for $700. This entry will correct the error so that the wages are expensed to the correct accounting periods.