On January 1, 2013, Mill Corporation purchased for $760,000, equipment having a useful life of ten years and an estimated salvage value of $40,000. Mill has recorded monthly depreciation of the equipment on the straight-line method. On December 31, 2021, the equipment was sold for $180,000. As a result of this sale, Mill should recognize a gain of

.

$68,000.

b.

$140,000.

c.

$0.

d.

$28,000.