Sam buys a used Camry from Best Motors, paying $2,000 down and agreeing to pay off the balance in thirty-six payments of $400 each. The terms of the agreement call for Sam to make a payment on or before the first of each month, beginning October 1. During the first six months, Best Motors receives a $400 payment before the first of each month. Starting in April and continuing for the subsequent five months, Sam's payment is never made until the fifth of the month Best Motors accepts and cashes the payment check each time. Before the next payment is due, Best decides that it is no longer willing to accept late payments