Solve the system by substitution.
-x-y-z=-8
-4x+4y+5z=7
2x+2z=4
Please walk me through this problem. I don't get how to do this with three equations. Thanks :)

Question

Solve the system by substitution. 
-x-y-z=-8
-4x+4y+5z=7
2x+2z=4
Please walk me through this problem. I don't get how to do this with three equations. Thanks :)

anonymous · Answer

well you can start by leaving each of the variables at one side.

anonymous · Answer

For example, 2z = -2x +4 -> z=-x +4
we can substitute this to 2x +2z =4
2x + 2(-x+4) = 4 -> 2x -2x +8=4 -> 0=-4 so x is 0

anonymous · Answer

therefore, if x is 0, then z must be 2

anonymous · Answer

so if we plug in the results that we've got so far x=0, z=2 into the equation -x-y-z=-8
0-y-2=-8 -> -y-2=-8 -> -y =-6 -> y= 6

anonymous · Answer

Therefore, x=0, y=6, z= 2

anonymous · Answer

Thank you sooo much :D

anonymous · Answer

welcome :)

anonymous · Answer

How come 0 can stand for x?

anonymous · Answer

the correct answer is actually y=6 
z=−1 
x=3