After graduating from high school, Jack Tern decided to become a truck driver. The A-OK Truck Driving Academy offered a two-week, intensive, one-on-one (instructor-student) course with training on two- and three-axle tractors and on 45-foot single and double trucks, for $4,000 cash. Because Jack had no money, A-OK agreed to take his written promise to pay the tuition fee in monthly installments of $130 for four years provided he could get a surety or guarantor to promise to pay if he defaulted. Jack’s Uncle Joe signed a guaranty agreement, and Jack enrolled and completed the course. After six months, however, he lost his job as a truck driver and could not continue making the monthly payments. Can A-OK immediately demand payment from Jack’s Uncle Joe?