One night at a restaurant, Mark and Mary wrote up an agreement on a couple of napkins about a construction project whereby Mark would build a room in addition to Mary's house.Mark said he would exchange for Mary agreeing to transfer an empty piece of land that she owned to Mark.It took two napkins because the agreement would not fit on a single napkin.Mark signed one of the napkins, but Mary signed neither.The contract price was $30,000.A few days later Mark saw the plans, which were more complex than he expected.Discuss the enforceability of this contract.