Question

(50 Points)

Which equation combines with the given equation to form a system of equations with the solution x = 3 and y = 9?
x + 2y = 21

Answer 1

x + 2y = 21
3 + 2(9) = 21
3 + 18 = 21
So I think the equation is 3 + 2(9) = 21

Answer 2

It's option C.

Explanation:

It's right on edmentum. Also just use substitution. Not that hard.