x:y=3:5,y:z=2:3求X+Y+Z/2X-Y+Z

问题描述:

x:y=3:5,y:z=2:3求X+Y+Z/2X-Y+Z

x:y=3:5
y:z=2:3
x:y:z=6:10:15
x=6k,y=10k,z=15k
X+Y+Z/2X-Y+Z
=6k+10k+15k/(12k-10k+15k)
=31/17