DeKalb Company wants to develop a cost function for its maintenance costs to estimate such costs for the coming year. The following data are available: Maintenance Direct Labour Hours Costs Incurred Month June 3,000 $1,000 July 6,750 1,718 August 8,000 1,800 September 5,500 1,290 Using the high-low method, what is the fixed maintenance cost? O A. $1,280 B. $520 C. $125 D. $90 Charleston Company has an average overhead cost per hour of $12.00 at 3,000 machine hours, and at 4,000 hours it is $11.25. The company managers wish to estimate the overhead cost function. What is the variable overhead cost per machine hour? $11.625 $11.00 $9.00 $8.00