x/5=y/3 x/7=z/3 2x-y-z=34
问题描述：
x/5=y/3 x/7=z/3 2x-y-z=34
答
x/5=y/3=t
x=5t,y=3t
x/7=z/3
z=(3/7)x=(15/7)t
2x-y-z=34
10t-3t-(15/7)t=34
(49-15)t=34*7
t=238/34
=7
x=5t=35,y=3t=21,z=(15/7)t=15
答
由已知得3x=5y=7z y=3/5x z=3/7x
将一直带入2x-y-z=34中
2x-3/5x-3/7x=34
解得x=35 y=21 z=15