Nova Company's total overhead costs at various levels of activity are presented below: Month Machine Hours Total Overhead Costs April 70,000 $198,000 May 60,000 $174,000 June 80,000 $222,000 July 90,000 $246,000 Assume that the total overhead costs above consist of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 60,000 machine-hour level of activity is: Utilites (variable) $48,000 Supervisory salaries (fixed) 21,000 Maintenance (mixed) 105,000 Total overhead costs $174,000 Nova companys management wants to break down the maintenance cost into its variable and fixed cost elements. Required: 1. estimate how much of the $246,000 of overhead cost in July was maintenance cost 2. Using the high-low method, estimate a cost formula for maintenance 3. Express the company's total overhead costs in the linear equation form Y = a + bX 4. What total overhead costs would you expect to be incurred at an operating level of 75,000 machine hours