Fifteen Years Ago Your Parents Purchased Some Land with the Idea

Short Answer

Fifteen years ago your parents purchased some land with the idea of selling it later to help pay your college expenses. They purchased the land for $100,000. They sold if for $180,000. During the time they held it the price level rose from 80 to 120. If your parents face a 25% tax rate, what was their real after-tax gain? (Hint: What's the real value of the land in current prices?)