Question 19511
Correct: z=4.
Now substitute that value into the original 3rd equation, as follows:  
-x + 3z =8
-x + 3(4)= 8
=x  = -4
 x = 4
Now substitute those values into the 1st equation to find "y".
2x + 3y -4z =4
2(4) + 3y -4(4) = 4
  3y -8 = 4
  3y = 12
   y = 4

Now you have x=y=z=4

Cheers,
stan H.