Given the following cost and activity observations for Smithson Company's utilities, use the high-low method to calculate Smithson's fixed costs per month.

	Cost	Machine Hours
January	$81,860	10,200
February	133,540	17,800
March	94,480	12,000
April	115,430	15,100

a.$40,000

b.$10,000

c.$12,500

d.$21,300