Can you help me with both problem number 1 and 2

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Solve the problem. a student earned grades of c, a, b, and a in four different courses. those courses had these corresponding numbers of credit hours: 4, 5, 1, and 5. the grading system assigns quality points to letter grades as follows: a = 4, b = 3, c = 2, d = 1, and f = 0. compute the grade point average (gpa) and round the result to two decimal places. 3.40 3.50 8.75 2.18

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?