Question 474015
-9x-9y-9z=27
-4x-7y+9z=-16
-5x-7y+2z=-2
---------
x + y + z = -3
4x+7y -9z = 16
5x+7y -2z = 2
---------------------
Use any method you know to get:
x = -7 
y = 5
z = -1
==========
Cheers,
Stan H.