Three different companies each purchased a machine on January 1, 2008, for $42,000. Each machine was expected to last five years or 200,000 hours. Salvage value was estimated to be $2,000. All three machines were operated for 50,000 hours in 2008, 55,000 hours in 2009, 40,000 hours in 2010, 44,000 hours in 2011, and 31,000 hours in 2012. Each of the three companies earned $30,000 of cash revenue during each of the five years. Company A uses straight-line depreciation, company B uses double-declining-balance depreciation, and company C uses units-of-production depreciation.