y=4-3x-2z
y=5-2x+z
4-3x-2z=5-2x+z
-x=3z+1
x=-3z-1
y=5+6z+2+z=7+7z
-3z-1-28-28z+2z=3
-29z=32
z=-32/29
x=96/29-1=87/29=3
y=7-224/29=-21/29