I need help on the journal entry for this... would it be:
dr. salaries expense 1600
Cr. Cash 1600

Or do I take into account that they were paid on the 20th?

August 20: Paid $1,600 for employee salaries (assume no payroll taxes were incurred).

If the question say they were acrued, this means that they were earned but not yet paid.

The journal entry is:
Debit Salaries Expense for the amount
Credit Salaries Payable for the amount

When the salaries are paid, then the journal entry is:
Debit Salaries Payable for the amount in the account
Deibt Salaries Expense for the difference
Credit Cash for the amount paid.

If your wages earned in the period are being paid in the period then the journal entry is:
Debit Salaries Expense for the amount
Credit Cash for the amount