Yes, the manager breached the contract by not fulfilling the actual offer made. The waitress should base her case on breach of unilateral contract. A unilateral contract is one in which the offeror commits to pay following the occurrence of a specific event. Unilateral contracts are most commonly utilized when an offeror has an open request for a specific act that they are ready to pay for. However, the waitress will have to prove that she did more than a reasonable person would have done achieve the sales.