Starling Co. is considering disposing of a machine with a book value of $20,600 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 71,400. 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 $23,500 to $19,900 if the new machine is purchased. The differential effect on income for the new machine for the entire five years is

a.increase of $48,400

b.increase of $62,920

c.decrease of $48,400

d.decrease of $62,920