1 x y z
2 x-y 2y z
3 x-y 2y-z 2z
4 2(x-y) 2y-z 2z-(x-y)
x+y+z=48
2(x-y)=2z-(x-y)
2(x-y)=2y-z
联立解方程得
x=22
y=14
z=12