On January 2, 2018, Sudbury Systems, a cell phone manufacturer, installed a computerized machine in its factory at a cost of $169,200. The machines useful life was estimated at four years or a total of 181,500 units with a $24,000 trade-in value. Sudburys year-end is December 31. Calculate depreciation for each year of the machines estimated useful life and the total depreciation for all 4 years under each of the following methods:

a. Straight-line

b. Double-declining-balance

c. Units-of-production, assuming actual units provided were:

Year	2018	2019	2020	2021
Units	38,300	41,150	52,600	56,000