On January 1, 2021, a machine was installed at Dunbar Factory at a cost of $53,000. Its estimated residual value at the end of its estimated life of 4 years is $20,000. The machine is expected to produce 66,000 units with the following production schedule:
• 2021: 8,000 units
• 2022: 25,000 units
• 2023: 18,000 units
• 2024: 15,000 units
Complete depreciation schedules for 

(a) Straight-line, 

(b) Units-of-production, and 

(c) Double declining-balance at twice the straight-line rate.