2206. Offer and acceptance in formation of contract. 2207. Additional terms in acceptance or confirmation.Offer and acceptance in formation of lease contract. 2A207. The general rule is that a contract is effective when both parties agree (ie, sign the Agreement of Sale) AND acceptance is communicated to the offering party. Generally, the elements of a legally enforceable contract are assent, a valid offer, acceptance, and consideration. Offer and Acceptance: One party must make an offer, and the other must accept it. Offer: One party must make a clear and definite proposal to another party.