Third-party woes. trudy owed sam $40 for a book she purchased from him. trudy mowed betty's yard for $40 and agreed with betty that betty would pay sam for the book. sam is not initially aware of the agreement. betty pays no one. trudy also mowed bob's yard for $40 in return for bob's agreement to give the payment to sally representing trudy's birthday present to sally. bob later refuses to do so saying that promises to give gifts are not enforceable. he then moves out of town. trudy tells both sam and sally that she is broke, that sam needs to get his $40 for the book from betty, and that sally is owed $40 from bob for her birthday present. which of the following is the likely result if sam sues betty for the $40 that trudy owes him for the book?