An Investment of $180 000 Yields Annual Net Returns of $27

Essay

An investment of $180 000 yields annual net returns of $27 700 for seven years. What is the rate of return on the investment (correct to the nearest tenth of a percent) if part of the initial investment, in the amount of, $80 000 is recovered at the end of 7 years?
a) Use linear interpolation to find the approximate value of the rate of return.
b) Find the answer using Cash Flow and IRR.