57. Northlake, Inc., uses the high-low method to analyze cost behavior. The company observed that at 20,000

machine hours of activity, total maintenance costs averaged $10.50 per hour. When activity jumped to

24,000 machine hours, which was still within the relevant range, the average total cost per machine hour

was $9.75. On the basis of this information, the company's fixed maintenance costs were:

A. $24,000.

B. $90,000.

C. $210,00.

D. $234,000.

E. an amount other than those listed above.