Production volume of 2,000 and 3,000 units, direct materials are $188,400 and $282,600, direct labor is $91,800 and $137,700, and the manufacturing overhead is $110,400 and $127,800. What is the best estimate of the total monthly fixed manufacturing cost?

what you do here is create a table where you identify what the movement in volume has done to the cost structure, this enables you to isolate the fixed component the following article discusses a number of concepts relating to fixed and variable cost;
http://faculty.weber.edu/rmcdermott/Acc%202020/PowerPoints%20McD/Cost%20volume%20profit%20revised%20march%203%2008. ppt#35