manna manufacturing purchased a machine on january 1, 2015 for $ 42,750. at the time of purchase. the machine was estimated to have a life of four years and a residual value of $7,750. on january 1, 2017, munna determined that the machine had a total useful life of seven years (another five years) and a residual value of $ 4500. if manna uses the straight line method of depreciation, what will be the depreciation expense for the machine in 2017?