On March 10, A wrote the letter to B "I am going to be away from May 1 to 30. If you take care of my apartments during that time i will pay for the food and other expenses if you wanna do this just show up on April 30th " B received the letter on Maech 12 and immediately wrote back telling A that he accepts. B mails the letter on March 13th and A receives it on March 17th. A for some resason cancels the offer by send revocation letter and B receives it on Maech 20th... is the contract formed or recoked???? Please those of you who know the answer help me out here thanks