How do you figure out your highschool GPA?

i forgot how to calculate it.How do you figure out your highschool GPA?
Any Grade Point Average is calculated like this:


';A'; = 4.0


';B'; = 3.0


';C'; = 2.0


';D'; = 1.0


';E'; = 0.0





[(Credit hours of course)*(grade point equivalent from above) + (same thing for all other courses)] / total credits


= overall GPA