Nineteen year old jill babysits for her neighbors every friday night for $50 and she gets paid at the end of the month . last friday she was not able to babysit for them because she went to a movie. the next week she went to her neighbor's house to babysit. they presented her with a contract stating that she must babysit for them every friday night for the next six months and she will earn $100 a night. they said she must sign the contract or she will only get paid $25 a night for the babysitting she did this month. why isn't this contract enforceable in a court of law?