Luster Consulting Company purchased a new heating and cooling system for their office building in March, 2014. After installing and testing the equipment, it was put into service on April 1, 2014. The total cost to put the equipment into service was $45,000; it is expected to have a useful life of 10 years and a salvage value of $5,000. On December 31, 2014, assuming Luster Consulting Company uses straight-line depreciation, what will be the amount of depreciation expense on the books?