The key answer of exercise 6

Maggie and Joe Smith lived in the same house for fifty years. When Joe died, Maggie sold the house to David Jones. A few weeks later, Maggie heard someone say that Jones had found some money in her old house. Jones told her there was $10,000 in the wall. He offered her $5,000. She agreed. A few days later, Jones asked Maggie to sign a contract that said she should accept $5,000 for any money found in or around the house. She didn't sign it. Instead, she took Jones to court. In court, he told the truth: there wasn't $10,000. There was $150,000. Joe Smith, Maggie's husband, was putting money in the wall for fifty years and he never told his wife. In the end, the judge decided that Maggie should get all of the money.