23. A company's total overhead cost at various levels of activity is presented below: Month Machine-Hours Total Overhead Cost March .. 5,000 $21,750 April .. 4,000 $19,000 6,000 $25,000 June ............. 7,000 $28,750 May. Assume that the overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 4,000 machine-hour level of activity is as follows: Utilities (variable) .... Supervisory salaries (fixed). Maintenance (mixed) ... Total overhead cost ........ $ 8,000 4,000 7,000 $19,000 Suppose the company uses the high-low method to estimate a cost formula for maintenance. What is the total maintenance cost the company expects to incur at an activity level of 7,600 machine hours? a. $12,640 b. $13,400 c. $12,800 d. $11,500 e. None of the above