How do you know if your facility is making money on group X classe

Karin i believe I asked this a little bit messy. Here is what I do now. I have memberships where they pay a monthly fee for taking classes & for the most part those members take an average 3 classes per week. I also have an annual membership as well that members can take classes. If you average that out per class it does not come to much per class maybe $5 & for annual memberships its even less. Taking all that information into account paying the instructors that teach them & utility costs etc. is how I figure things out, so I am not sure if this is the correct way or is there a better strategy? Thank you!