Jennifer and Tara are long-time friends. Tara has a birthday party for her 2 year old twins. Jennifer helps Tara out with the party, coming 2 hours before, and staying 1 hour after, to help with set up and with clean up after. The next day, Tara promises to Jennifer that she will pay Jennifer $200 because of all the help Jennifer provided the day before at the party. Is Tara's promise enforceable?