Nighthawk Inc. is considering disposing of an old machine with a book value of $22,500 and an estimated remaining life of three years. The old machine can be sold for $6,250. A new machine with a purchase price of $68,750 is being considered a replacement. It will have a useful life of three years and no residual value. It is estimated that the annual variable manufacturing costs will be reduced from $43,750 to $20,000 if the new machine is purchased. The three-year differential effect on profit from replacing the machine is a n) .$2,925 decrease b.$8,750 decrease c.$8,750 increase d.$31,250 decrease (Ctrl)