Edward and Tony are fraternity brothers. Edward has a dinner party to celebrate getting a new job. Tony helps Edward out with the dinner party, coming 3 hours before, helping with cooking, buying the ingredients for the dinner, and party set up, and staying after, to help with clean up after. The next day, Edward promises Tony that Edward will pay Tony $100 because of all the help Tony provided the day before at the dinner party. Is Edward's promise enforceable? Why or why not?