Solomon Rentals can purchase a van that costs $170,000; it has an expected useful life of five years and no salvage value. Solomon uses straight-line depreciation. Expected revenue is $61,965 per year. Assume that depreciation is the only expense associated with this investment. Required a. Determine the payback period. Note: Round your answer to 1 decimal place. b. Determine the unadjusted rate of return based on the average cost of the investment. Note: Round your answer to 1 decimal place. (i.e., .234 should be entered as 23.4)