assume that labor is the only variable input .if a firm's short-run marginal cost is increassing as output rises , which of the following must be true ?

Warren company plans to depreciate a new building using the double declining-balance depreciation method. the building cost $870,000. the estimated residual value of the building is $57,000 and it has an expected useful life of 20 years. assuming the first year's depreciation expense was recorded properly, what would be the amount of depreciation expense for the second year?