How do i do this numbers 26-28 like what equation would u use to solve

Astudent received the following grades last semester. find the student's semester grade point average. an a is algebra (3 credits), a b in history ( 3 credits), a in sociology ( 3 credits) a d in english ( 3credits) and a c in seminar ( 2credits). an a is worth 4 points, a b is worth 3 points a c is worth 2 points and a d is worth 1 point.

How is working backward similar to solving an equation?

60 2(x + 2) in the diagram, gef and hef are congruent. what is the value of x?