Answer:
I believe that the contract for the additional $12,500 is a valid contract but can be voided by the Hoffmans if they prove that duress was established, so it is a voidable contract.
Explanation:
In legal terms duress means that someone was illegally forced to accept a contract or perform an action. In this case the Hoffmans were victims of duress since All-Right's foreman forced them to accept the price increase or there house would be in bad shape due to rain. It's like a doctor asking more money in the middle of an operation or else he will stop operating.