Starling Co$.$ is considering selling a machine with a book value of $$24,400$ and estimated remaining life of $5$ years. The old machine can be sold for $$5,500.$ A new high$-$speed machine can be purchased at a cost of $$74,300.$ It will have a useful life of $5$ years and no residual value. It is estimated that the annual variable manufacturing costs will be reduced from $$22,900$ to $$20,600$ if the new machine is purchased. The differential effect on profit for the new machine for the entire $5$ years is a$($n$)$

a$.$ decrease of $$57,300$

b$.$ increase of $$74,490$

c$.$ increase of $$57,300$

d$.$ decrease of $$74,490$