Javier promises to pay his employee Tyson, who is obese, $5 for every pound that he loses within the next nine months. Tyson agrees and ultimately loses 200 pounds. When Tyson asks Javier to pay him the agreed upon amount, Javier refuses to pay, stating that he never made such a promise. Tyson subsequently sues Javier. In whose favor is the court likely to rule, and why?