John has a lending company. In his letter mailed on September 15, he offered to sell his business to Peter for $20,000. The letter was received by Peter on September 20. On September 25, Peter sent his letter of acceptance in which John received on September 28. However, on September 23, John had decided to withraw and mailed a letter to peter revoking it. The letter was not received until September 29. Issue:Did the contract form? When?