40 - [(8 x 7) - (5 x 6)] need the work also

Write a function for a rotation 90 degrees counter clockwise about the origin, point 0

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

What is the value of x when x + 7 = 21?