Sheffield Taxi Service uses the units-of-activity method in computing depreciation on its taxicabs. Each cab is expected to be driven 141,000 miles. Taxi no. 10 cost $31,000 and is expected to have a salvage value of $1,390. Taxi no. 10 is driven 32,000 miles in year 1 and 22,500 miles in year 2. (a1) Calculate depreciable cost per mile using unit-of-activity method. (Round answer to 2 decimal places, e.g. 0.50.) Depreciable cost per mile