25 The XYZ Block Company purchased a new office computer and other depreciable computer hardware for $12,000. During the third year, the computer is declared obsolete and is donated to the local community college. Using an interest rate of 10%, calculate the PW of the depreciation deductions. Assume that no salvage value was initially declared and that the machine was expected to last 5 years. (a) Straight-line depreciation (b) Sum-of-years'-digits depreciation (c) MACRS depreciation (d) Double declining balance depreciation (e) Which method is preferred for determining the firm's taxes? (f) Which method is preferred for determining the firm's value? (g) Is using two accounting methods ethical