Zack is at home when someone knocks on his door. Zack answers the door and a guy named Stone, dressed in painter's overalls and carrying buckets of paint, says, "I see that

your house needs painting. I'll do it for you and it'll look great." Zack rolls his eyes and

responds, "Hmm, whatever," and closes the door. Several hours later, Stone knocks on Zack's door. Zack answers. Stone says, "See, look. I painted your house. It looks great. That'll be $500.00." Zack says, "No, I'm not paying," and slams the door in Stone's face. Stone sues Zack in small claims court for $500.

What is the IRAC regarding contracts?