I need the answers asap (3)

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 to do a maths question? i have a mock

You have z baseball cards. christopher has 12 fewer baseball cards than you do. which expression correctly shows how many baseball cards christopher has?