1 The cost of equipment purchased by Charleston Inc. Oon June 1, 2017 is $89,000. It is estimated that the machine will have a $5,000 salvage value at the end of its service life. Its service life is estimated at 7 years, its total working hours are estimated at 42,000 and its total production is estimated at 525,000 units. During 2017 the machine was operated 6,000 hours and produced 55,000 units. Buring 2018 the machine was operated 5,500 hours and produced 48,000 units. Compute depreciation expense on the machine for the year ending December 31, 2017, and the year ending December 31, 2018, using the following methods Straight Line Units-of-output working hours Sum-of-the-years-digits Declining Balance (twice the SL rate)