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 $64,110 10,100 February 106,950 18,500 March 76,730 12,500 April 87,310 14,600 a. $21,400 b. $40,300 c. $12,600 d. $10,100