(x+2y)÷3=(2y-3z)÷6=(x-3z)÷9 ，变为2（x+2y)=2y-3z,3(x+2y)=x-3z,又变为2x+2y=-3z=2x+6y,∴y=0,x=-3z/2,①1/2 x+y-3/2 z=9，②把①代入②，-9z/4=9,z=-4,代入①，x=6,∴{x=6, {y=0, {z=-4.
