Davis Machine Works purchased a stamping machine for $135,000 on February 1, 2012. The machine is expected to have a useful life of 10 years, salvage value of $12,000, production of 250,000 units, and number of working hours of 30,000. During 2012, Davis used the stamping machine for 2,450 hours to produce 23,450 units. From the information given, compute the book depreciation expense for 2012 under each of the following methods:
(a) Straight‐line
(b) Units of production
(c) Working hours
(d) Double‐declining‐balance (without conversion to straight‐line depreciation)