On March 20, 2000, a customer approaches a to Star Bank, a hypothetical company, and requests to purchase him a quadbike. On March 25, 2000 both agrees that the bank will buy the quadbike to the customer at the market price of $4,000 but the customer will have to pay back $5,000 to the bank in 3 years on deferred payments basis. What kind of sales contract is this? Why?