Layton Company purchased tool sharpening equipment on October 1 for $39,960. The equipment was expected to have a useful life of 3 vears or 6,480 operating hours, and a residual value of $1,080. The equipment was used for 1,200 hours during Year 1,2,300 hours in Year 2,1,900 hours in Year 3 , and 1, 080 hours in Year 4. Required: Determine the amount of depreciation expense for the years ended December 31, Year 1, Year 2 , Year 3, and year 4, by (a) the stralght-ine method, (b) the units-citactivity method, and (c) the double-declining-balance metiod. Note: FOR DECITNING BALANCE ONLY, round the multiplier to four declmal places. Then round the answer for eacla year to the nearest whole dollar. a. Straight-line method b. Units-of-activity method c. Double-declining-balance method