x:y=3:2
2x=3y
x=3y/2①
y:z=5:4
4y=5z
z=4y/5②
x-y-z=66③
代①和②入③
3y/2-y-4y/5=66
y=-220
∴x=-220×3/2=-330
z=-220×4/5=-176
即：方程组的解为x=-330；y=-220；z=-176