Answer:
Deangelo has defaulted on the contract.
Step-by-step explanation:
A party to a contract is said to have defaulted on a contract when a non material breach of a contract occurs. One of the parties to the contract fails to meet his obligations.
So the failure to do what is expected within a given time frame will result in default of the contract. The contract can now be cancelled.
In the given instance DeAngelo had an obligation to mediate the radon gas problem in his basement within 31 days.
He has failed to do this at the end of 31 days so he has defaulted on the contract