A company purchased a piece of equipment for $23,000 on May 1, 2015. It estimates a residual value of $2,500, a useful life of 4 years and estimated productive life of 10,000 units. It produced 2,000 units in 2015. What is depreciation expense for 2015 using the units-of-production method (rounded to nearest dollar)? a. $3,417 b. $5,125 c. $4,100 d. $2,733