Answer:
Andrew can sue Robert for breach of contract.
Step-by-step explanation:
A contract case is presented before a judge if one or both parties claim that contract has been breached.
A breach of contract is like a failure to fulfill the promise that was a part of the contract. This is in legal terms. It can allow a party to sue the other party for making a contract breach.
Robert breached the contract as he did not pay the commission on the sale of his house to the buyer. So, Andrew can sue Robert for the same.