Can someone please help me compute the cash payback period and the annual rate of return?

Legend Service Center just purchased an automobile hoist for $34, 400. The hoist has an 8-year life and an estimated salvage value of $3, 950. Installation costs and freight charges were $4, 020 and $840, respectively. Legend uses straight-line depreciation. The new hoist will be used to replace mufflers and tires on automobiles. Legend estimates that the new hoist will enable his mechanics to replace 6 extra mufflers per week. Each muffler sells for $76 installed. The cost of a muffler is $40, and the labor cost to install a muffler is $13. Compute the cash payback period for the new hoist. (Round answer to 2 decimal places, e.g. 10.50.) Compute the annual rate of return for the new hoist. (Round answer to 1 decimal place, e.g. 10.5.)