I need help answering the following question.

In 1803, the U.S. doubled in size with the Louisiana Purchase. That well-known real estate

mogul Napoleon Bonaparte sold us 827,000 square miles (529,280,000 acres-there are 640 acres

in a square mile). We paid $15 million. Assume that part of the US is worth an average of $5,500

per acre in 2018. What is the annual rate of return of this purchase for the U.S.?