Liang and Cruz Deliveries is the world's leading express-distribution company. In addition to its 643 aircraft, the company has more than 57,000 ground vehicles that pick up and deliver packages. Assume that Liang and Cruz sold a delivery truck for $31,000. Liang and Cruz had originally purchased the vehicle and recorded it in the Truck account for $51,000 and had recorded depreciation for three years. Required: Calculate the amount of gain or loss on disposal, assuming that Accumulated Depreciation-Truck was (a) $20,000, (b) $16,000, and (c) $26,000. (Select "None" if there is no Gain or Loss.)