Solve the system: {x+y+z=62x−y+z=4x+2y−z=4\begin{cases} x + y + z = 6 \\ 2x - y + z = 4 \\ x + 2y - z = 4 \end{cases}⎩⎨⎧x+y+z=62x−y+z=4x+2y−z=4 What is the value of x+2y−2zx + 2y - 2zx+2y−2z?
000
222
444
666