Abby is a brilliant 16-year-old high school student who has invented "The Spritzer," a device to keep vegetables fresh in the refrigerator. Abby goes to TGIThursdays restaurant, where she meets up with Brianna, the 23-year-old sister of Abby's best friend. They sit down for a bite to eat. Brianna has four vodka-and-tonics, Abby has a Coca-Cola. Brianna and Abby writes a contract on a sheet of paper, and sign it, stating that Brianna promises to pay Abby $100,000 for all rights in The Spritzer. Is this a valid contract? What are the reasons why this might not be a valid contract?