Answer:
Unilateral Mistake
Step-by-step explanation:
In a contract between two parties, a unilateral mistake occurs when one party in the contract makes a mistake regarding cost, the definition of a term or word, or measurement. The outcome of such a mistake is usually a conflict between the two parties. To resolve this problem, the contract could be canceled (if the other party becomes aware of the mistake), or reformed (if only one party is aware of the mistake).
When Mark made a mistake about the cost of building the house for David, he made a unilateral mistake as the mistake was committed by him alone. David's refusal of the amended cost is resulting in a conflict that would likely lead to the cancellation of the contract.