A company purchased factory equipment on April 1, 2007, for $48,000. It is estimated that the equipment will have a $6,000 salvage value at the end of its 10-year useful life. Using the straight-line method of depreciation, the amount to be recorded as depreciation expense at December 31, 2007, isa. $4,800b. $4,200c. $3,150d. $3,600