已知:x/3=y/5=z/7,2x+y-z=8,求:3x+2y-z的值.

问题描述:

已知:

x
3
y
5
z
7
,2x+y-z=8,求:3x+2y-z的值.

x
3
y
5
z
7
=k,则x=3k,y=5k,z=7k,
又2x+y-z=8,则6k+5k-7k=8,k=2,
即x=6,y=10,z=14,所以3x+2y-z=3×6+2×10-14=24.