x=17-2y
y=4+3z
-3z=4-y⇒z=[tex] \frac{4-y}{-3} [/tex]
2(17-2y)+4(4+3z)*17-2y+4(4+3z)-6([tex] \frac{4-y}{-3} [/tex])
34-4y+16+12z*17-2y+16+12z-6/[tex] \frac{4-y}{-3} [/tex]=34+16*17+16-6/[tex] \frac{4-y}{-3} [/tex]-4y+12z-2y+12z=[tex] \frac{-645}{1-y} [/tex]-6y+24z;
