Question 1015260
2x+2y-8z=8
5x+y-z=8
-x-y+4z=2

This is 3 equations in 3 unknowns, i.e. 3 variables. We need to manipulate to get to 2 equations /2 unknowns, by combining 2 at a time. 

2x+2y-8z=8  (EQ1)
-2x-2y+8z=4  (EQ3 multiplied by 2)

All terms cancel, adding to zero. There is no unique solution.