Starling Co. is considering disposing of a machine with a book value of $21,500 and estimated remaining life of five years. The old machine can be sold for $5,000. A new high-speed machine can be purchased at a cost of 69,600. It will have a useful life of five years and no residual value. It is estimated that the annual variable manufacturing costs will be reduced from $22,800 to $19,600 if the new machine is purchased. The five-year differential effect on profit from replacing the machine is a(n)

a.increase of $63,180

b.decrease of $48,600

c.decrease of $63,180

d.increase of $48,600