Determining cost behavior with the high-low points method. The monthly supervisory costs of the Able Company’s factory for each month of 19X1 have been analyzed. The month in which the greatest number of direct labor hours were worked was March, with 10,000 hours. The supervisory costs for that month totaled $80,000. In July, the month of fewest direct labor hours, 6,800 hours were worked, and supervisory costs were $64,000. Use the high-low points method to do the following:

a. Compute the variable cost per direct labor hour using the high-low points method.

b. Compute the fixed cost per month.