EE 10-3 456 OBI. PE 10-3A Units-of-output depreciation A tractor acquired at a cost of $275,000 has an estimated residual value of $39.000 an estimated useful life of 40,000 hours, and was operated 2,660 hours during the Determine (a) the depreciable cost, (b) the depreciation rate, and (c) the units-of-out depreciation for the year