Year xRate = Yearly Depreciation
1800,000$ 0.400000 320,000$
2480,000$ 0.400000 192,000$
3288,000$ 0.400000 115,200$
4172,800$ 0.400000 69,120$
Since depreciation cannot cause book value to fall below residual value:
Year −= Yearly Depreciation
5103,680$ 90,000$ 13,680$
2.
696,320
135,000
800,000
31,320