double diminshing balance??????

Q3. On January 3, 2016, B.W. Soffer Inc. paid $224,000 for a computer system. In addition to the basic purchase price, the company paid a setup fee of $6,200, $6,700 sales tax, and $3,100 for special installation. Management estimates that the computer will remain in service for five years and have a residual value of $15,000. The computer will process 50,000 documents the first year, decreasing annually by 5,000 during each of the next four years (that is, 45,000 documents in 2017, 40,000 documents in 2018, and so on). In trying to decide which depreciation method to use, the company president has requested a depreciation schedule for each of three depreciation methods (straight-line, units-of-production, and double-diminishing- balance). Requirement