Buisness law

On June 1st, Sam mailed Bob an offer to sell his motorcycle for $4,000. Bob got the offer on June 2nd, and ignored it. On June 3rd, Sam decided to mail a revocation. This revocation letter was lost in the mail so Bob never received it. June 5th, Bob decided to accept the offer and mailed Sam an acceptance. Sam got this letter on June 6th. Sam claimed no contract existed since he revoked his offer before B accepted.

1.Who wins and on what legal principles is your answer based? Explain fully.