This is an example.
Change the Courses, Credits, Weightings and Results as required
Results
Weighting **  
N Course Credits */Term 12345678910 Average
1  
2  
3  
4  
5  
6  
7  
8  
9  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
Raw Average             
Weighted Average             

Setting all the credits to the same value will produce 2 identical averages.
* The number of credits is usually the last digit of the course.
** Set the weight to identical values if the terms are weighted equally.
Set the weight to zero or blank if the term does not count.