Oscar Olson, single, purchased a residence on February 19, 2016, for \(\$ 170,000\). On September 7, 2018, a tornado completely destroyed his home. The home was insured for its replacement value, and homes in Oscar's area had appreciated greatly. He received proceeds of \(\$ 400,000\).

a. How much does Oscar exclude and recognize?

b. If Oscar instead had received proceeds of \(\$ 525,000\), how much gain would be excluded and recognized? How much of a replacement residence would have to be purchased in order to exclude or defer all gain realized?