已知4x=5y,那么(3x+y)/(x-2y)=

问题描述:

已知4x=5y,那么(3x+y)/(x-2y)=

(3*5+4)/(5-2*4)=-19/3;
用数字吧,做选择题快些

4x=5y
X=5y/4
(3x+y)/(x-2y)
=(15y/4+y)/(5y/4-2y)
=(19y/4)÷(-3y/4)
=-19/3

y=4x/5
所以原式=(3x+4x/5)/(x-8x/5)
=(19x/5)/(-3x/5)
=-19/3