Question

Consider the system of equations.



−
3
x
+
5
y
=
9

3
x
−
7
y
=
3



What is the
x
-coordinate of the solution for this system?

A.
−
15

B.
−
13

C.
13

D.
15

Answer 1

Add the equations to eliminate x:
(-3x+5y) + (3x-7y) = 9+3 → -2y = 12 → y = -6.
Substitute into 3x - 7y = 3:
3x - 7(-6) = 3 → 3x + 42 = 3 → 3x = -39 → x = -13.

Answer: B.