Emma purchased a new lawn mower yesterday for $350 from the local home improvement warehouse. When she arrived home and attempted to use the new mower, it would not start. Exasperated, Emma yelled "I'd sell this stupid mower for $50." Emma's's next-door neighbor Jacobi overheard her (Emma was not aware that Jacobi was home at the time). Jacobi quickly replied, "I'll take it!" and immediately brought her $50. What are the valid elements of an offer? Is this situation a valid offer? Identify 3 reasons to explain your response.