Starling Co. is considering disposing of a machine with a book value of $20,000 and estimated remaining life of five years. The old machine can be sold for $6,000. A new high-speed machine can be purchased at a cost of $69,300. 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 $23,200 to $19,500 if the new machine is purchased. The differential effect on income for the new machine for the entire five years is a(n)

a.decrease of $44,800

b.increase of $58,240

c.increase of $44,800

d.decrease of $58,240