In this case Tony would just like to provide this sales quote and has a prescribed time. Tony said: "I have limited supplies and its offer ends at 5pm today." Therefore the expiry date is 5pm. Acceptance must take place within a reasonable time and, if the expiry date is set at 5pm, after this time the offer will lose effectiveness. So, after 5pm, Emma would like to receive this counter-offer and pay $1,900 to purchase this TV, however Tony rejects her because the counter-offer has expired. Consideration is an aspect of the concept of mutuality underlying the legal contract, and consists of each contracting party bargaining and giving in exchange for the other party's promise of restitution or performance. In this case the consideration is enforceable and the price of $1,900 has a legal value, so the consideration is sufficient and the original price that Tony would like to sell is $1,900 and Emma received this price, so the consideration is adequate. Therefore, there is a valid