aloha company purchased constructuction equipment on january 1, 2019 for $500000. the equipment is expected to have a useful life of four years or 50000 hours and a salvage value of $50000. the equipment was used for 14700 hours during 2019, 13900 in 2020, 11900 hours in 2021, and 9500 in 2022. determine the amount of depreciation expense for each four years by (a)straightline depreciation and (b) the units of production method, and (c) the double declining balance method.