Why do economists typically prefer to show the business cycle with a flat trend line?

Bayside coatings company purchased waterproofing equipment on january 2, 20y4, for $190,000. the equipment was expected to have a useful life of four years and a residual value of $9,000. instructions: determine the amount of depreciation expense for the years ended december 31, 20y4, 20y5, 20y6, and 20y7, by (a) the straight-line method and (b) the double-declining-balance method. also determine the total depreciation expense for the four years by each method. depreciation expense year straight-line method double-declining-balance method 20y4 $ $ 20y5 20y6 20y7 total $