Why is this the answer?

Question 21 0/1 point At the end of the current month, a company had an ending balance in the Accounts Payable account of $22,000. Purchases on account during the current month amounted to $16,600. If the balance in the Accounts Payable account at the end of the previous month was $27,200, what is the amount paid to creditors for purchases on account, during the current month? a) $21,800 b) $65,800 c) $32,600 d) Cannot be determined