Formula needed: Averages per user based on text contained in another cell

Hi,
I am in need of a formula (or other suggestion/idea) on how to calculate averages for each user based on whether or not they have grades in part A and part B of the same class. For example, if user 1 is in English 10 A and English 10 B, they should have grades for both of these sections. I need to avereage those 2 grades for one final English 10 grade.

The difficulty is that there are 4000+ users with a large variety of courses.

Some of these courses do not have part A & part B. Those classes can be ignored as their current grade is the average for that class.
I have attached an small example of what my current pivot table looks like for each user.
I am open to any ideas or suggestions you may have.
Please let me know if you need further information.
Thank you for your time!