7.4

The book answers is A) 38% and B)$32, I want to know all steps for it.

The Diagonal Stamp Company, which sells used postage stamps to collectors, advertises that its average price has increased from $1 to $5 in the last 5 years. Thus, management states, investors who had purchased stamps from Diagonal 5 years ago would have received a 100% rate of return each year. What is the annual rate of return