Billy the Bartender sees that Sally has had too much to drink. Billy offers to take Sally home. Jill and Billy load Sally into Billy's car and Billy drives Sally home. The next day Jill tells Sally what Billy did. Sally agrees to treat Billy to a steak dinner in return for Billy driving her home. However, Sally finds out that Billy likes Jill and was just trying to impress Jill, so she refuses to honor her promise.Can Billy enforce Sally's promise? Explain your answer fully.