Question

3x-2y+2z=30
-x+3y-4z= -33
2x-4y+3z=42

Answer 1

Ok are doing systems of equations

Answer 2

First 3x-2y+2z=30
-3x+9y-12z=99
+--------------------- add both equations together

Answer 3

7y-10z= 129 But if you take 3 times - 33 you get -99. How did you get +99?

Answer 4

You multiplied -x+3y+4z=-33 by 3