HD and D= 4 points
C= 3 points
P= 2 points
PC= 1 point
F= 0
So for example, if you got 2 C's and 2 P's, it'll give you 10. Then you divide by the amount of units, this case 4, so it would be 10/4= GPA of 2.5.
Just combine all semesters and units to get your GPA.