Exercise 11-6 Riverbed Company purchased equipment for $218,925 on October 1, 2017. It is estimated that the equipment will have a useful life of 8 years and a salvage value of $12,600. Estimated production is 39,300 units and estimated working hours are 19,900. During 2017, Riverbed uses the equipment for 520 hours and the equipment produces 1,000 units. Compute depreciation expense under each of the following methods. Riverbed is on a calendar-year basis ending December 31. (Round rate per hour and rate per unit to 2 decimal places, e.g. 5.35 and final answers to 0 decimal places, e.g. 45,892.) (a) Straight-line method for 2017 $ (b) Activity method (units of output) for 2017 $ (c) Activity method (working hours) for 2017 $ (d) Sum-of-the-years'-digits method for 2019 $ (e) Double-declining-balance method for 2018 $