A truck acquired at a cost of $80,000 has an estimated residual value of $8,000, has an estimated useful life of 200,000 miles, and was driven 18,000 miles during the year. Determine the following. If required, round your answer for the depreciation rate to 2 decimal places. (a) The depreciable cost (b) The depreciation rate per mile (c) The units-of-activity depreciation for the year