Final answer:
Monique and Gregory's agreement for a tennis lesson in exchange for $50 represents a bilateral contract where both parties have made a promise to each other.
Step-by-step explanation:
In the scenario presented, Monique offers to pay Gregory $50 for a tennis lesson for her daughter Hannah, and they agree to meet to exchange the cash for the lesson. This situation is indicative of a bilateral contract, where both parties have expressly communicated and agreed upon the exchange of a service (tennis lesson) for payment ($50).
A bilateral contract involves two parties where each promises to perform an act in exchange for the other party's act. By contrast, a unilateral contract involves one party making a promise in exchange for the other party's performance, not a promise of performance. A third-party contract would involve someone who is not a direct participant in the contract. In this case, since both parties are making promises and intend to fulfill them, it is a bilateral contract.