Hannibal owns a farm. He purchases a tractor in 2012 at a cost of $25,000. Because 2012 is a bad year, he does not deduct any depreciation on the tractor in 2012. He sells the tractor in 2016 for $16,000. He takes straight-line depreciation on the tractor of $12,500 for the years 2013 to 2016. The total allowable straight-line depreciation for the tractor for 2012 to 2016 is $15,000. What is Hannibal's gain or loss on the sale of the tractor? Explain.