On Jan 1, ABC Co. purchased a piece of equipment for $280,000, $30,000 salvage value, 4 year useful life. The equipment is estimated to produce 500,000 units over its life. Actual units produced were 125,000; 100,000; 175,000; 100,000 for years 1-4, respectively. Determine depreciation for each year under straight line, units of production, and double declining balance.

Part B. At the end of year 3 (prior to recording depreciation expense for that year) ABC Co changed the estimated useful life to 6 years and salvage value to $35,000. What is the updated depreciation expense under straight line?