Oahu Inc. is considering an investment in new equipment that will be used to manufacture a smartphone. The phone is expected to generate additional annual sales of $3,900$ units at $$256$ per unit. The equipment has a cost of $$399,000,$ residual value of $$30,000,$ and an $8-$year life. The equipment can only be used to manufacture the phone. The cost to manufacture the phone follows:

Line Item Description Amount

Cost per unit:

Direct labor $$42\mathrm{.}00$

Direct materials $164\mathrm{.}00$

Factory overhead $($including depreciation$)28\mathrm{.}55$

Total cost per unit $$234\mathrm{.}55$

Determine the average rate of return on the equipment. If required, round to the nearest whole percent.