Chu, a non-swimmer, fell off a ferry boat into the lake. "Help!" he cried. "$500 to the person who saves me!" Frances, a passenger on the ferry, then jumped in and held Chu's head above water and pulled Chu to shore. Once Chu and Frances were on shore, Chu refused to pay Frances. Please advise Frances whether Chu can refuse to pay Frances by referring to relevant concept(s) in contracts.

While George was visiting his physician Dr. Smith, he mentioned to Dr. Smith that he wished to sell his expensive sailboat. Dr. Smith expressed an interest in buying the boat and offered to pay George $6,000 for it. George had intended to advertise the boat for $12,000 in the local newspaper. But George agreed to sell it to Dr. Smith for $6,000 because George was completely dependent on Dr. Smith for medical care and was afraid that Dr. Smith would stop treating him if he did not agree to sell the boat. Two days after the boat had been sold to Dr. Smith; George wished to avoid the contract. Please advise George of his legal rights.