Question

-3x+7y=-16
-9x+5y=16

Answer 1

Multiply each term on the first equation by (-3).
Now, you get: 9x-21y=48
now, you add both equations.
9x-21y=48
+(-9x)+5y=16
(-9x) and 9x cancells out, (-21y) and 5y combined is (-16y), and 48+16 is 64.
The new equation should look like this:
(-16y)=64
Solv for y, and then plug in the value for y into any of the two equations and then solve for x.