On January 1, 20x1, Zane Manufacturing Company purchased a machine for $40,000. The company expects to use the machine a total of 24,000 hours over the next 6 years. The estimated salvage value of the machine at the end of 6 years is $4,000. The company used the machine 8,000 hours in 20x1 and 12,000 in 20x2. What is depreciation expense for 20x1 if the company uses units-of-production depreciation