Here's a test for you! I will provide answer after solved.

Substitute for x and z

-6y + y +14y = -54

9y = -54

y = - 6

z=14y = 14(-6) =- 84

x = -6y = -6(-6) = 36

Good job! BUT DO THEY ADD UP IS THEY QUESTION???? ;D

Yes they do add up    

x+y+z = 36 -84-6 = -54    CHECK!

I know that :|

I was saying he should check (even tho he was right)