Joe, a university student, parked his car near Harry's garage and went away to attend classes. Harry had noticed that there was glass on the street when he came to work that morning and was not surprised when he saw that several of the students' cars parked in that location subsequently had at tires. He went around when he had time during the day, to each of those cars, fixed the tires and put a bill on each vehicle charging $15 for the service. Joe had come back during the day and noticed his flat tire, and when he came back that evening was grateful that it had been fixed. He went over to the garage to thank Harry and told him that he would be happy to pay the $15, but he couldn't do it until next week. In fact, he failed to pay the money, and Harry sued him for breach of contract. Explain the likely outcome.