On April 1, 2013, Parks Company purchased machinery at a cost of $42,000. The machinery is expected to last 10 years and to have a residual value of $6,000. Show all work and compute the depreciation expense for 2013 and 2014 assuming: a. Parks uses the straight-line depreciation method. b. Parks uses the sum-of-the-years-digits depreciation method. c. Parks uses the double-declining balance depreciation method