Caribou Company purchased tool sharpening equipment on July 1, 2005, for $194,400. The equipment was expected to have a useful life of three years, or 22,950 operating hours, and a residual value of $10,800. The equipment was used for 4,650 hours during 2005, 7,500 hours in 2006, 7,350 hours in 2007, and 3,450 hours in 2008.

Instructions
Determine the amount of depreciation expense for the years ended December 31, 2005, 2006, 2007, and 2008, by
(a) The straight-line method,
(b) The units-of-production method, and
(c) The declining-balance method, using twice the straight-line rate.