Starling Co. is considering disposing of a machine with a book value of $23,100 and estimated remaining life of five years. The old machine can be sold for $5,400. A new high-speed machine can be purchased at a cost of 72,400. 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 $22,900 to $20,100 if the new machine is purchased. The five-year differential effect on profit from replacing the machine is a(n)

a. increase of $53,000

b. decrease of $53,000