Sketches Inc. purchased a machine on January 1, 2016. The cost of the machine was $39,500. Its estimated residual value was $12,500 at the end of an estimated 5-year life. The company expects to produce a total of 10,000 units. The company produced 1,450 units in 2016 and 1,900 units in 2017. Required: a. Calculate depreciation expense for 2016 and 2017 using the straight-line method.