Please answer A, B and C

A robot has just been installed at a cost of $81,000. It will have no salvage value at the end of its useful life. (a) What are the expected savings per year, life, and corresponding rate of return for the expected values? (b) Compute the rate of return for each combination of savings per year and life. What is the expected rate of return? (c) Do the answers for (a) and (b) match? Why or why not