What is the difference in a weighted and unweighted gpa?

An unweighted GPA is just your grades on a 4 point scale. F=0 points, D=1 point, C=2 points, B=3 points, A=4 points. (-A’s, A’s, and A+’s are all worth different points, but it’s just a basic explanation. Applies to all letter grades, not just A. But all F’s are zero). A weighted GPA is what colleges mostly look at to see what vigor of classes you’re taking. In honors classes, you get half a point for grades C, B, and A (4.0 turns into 4.30ish). In AP classes you get 1 extra point for C, B, and A (4.0 to 5.0)

I don't know if you mean the equation simplified, but the first property to any equation or expression is "given." (without the quotation marks, of course.)