Problem Scenario: Amy lives alone, but has always been very fond of her cousin, Beryl, who lives in the same village with her family (Charlie, her husband, and David, her son). When Beryl tells her that Charlie has lost his job and that they are suffering from financial difficulties, Amy offers to help. She offers to give David, who is in his final year at university, £1,000, provided that he works hard and obtains a second class degree. Amy also agrees to pay Beryl £300 for all the errands she has run for her in the past. Beryl is pleased as she had, selfishly, expected some payment for all his effort. Amy also agrees that, although Charlie owes her £1,000, she will accept £500 instead. Charlie pays Amy £500. David, who is exceptionally intelligent, does little work, but manages to obtain a first class degree. As a result, he obtains a lucrative graduate training post in a merchant bank. Advise Amy, who has now quarrelled with Beryl and wishes to know to what extent she is bound by her promises. Would it make a difference if Beryl paid Amy the £500?