A tractor acquired at a cost of $420,000 has an estimated residual value of $30,000, has an estimated useful life of 25,000 hours, and was operated 1,850 hours during the year. Determine (a) the...

A tractor acquired at a cost of $420,000 has an estimated residual value of $30,000, has an estimated useful life of 25,000 hours, and was operated 1,850 hours during the year. Determine (a) the depreciable cost, (b) the depreciation rate, and (c) the units-of-output depreciation for the year.