Strait Co. manufactures office furniture. During the most productive month of the year, 3,000 desks were manufactured at a total cost of $59,000. In the month of lowest production the company made 1,125 desks at a cost of $38,000. Using the high-low method of cost estimation, total fixed costs are
a. $21,000
b. $25,400
c. $42,000
d. $13,000