应该是b+2d-f不等于0
a/b=c/d=e/f=2/5
则a=2b/5,c=2d/5,e=2f/5
(a+2c-e)/(b+2d-f)
=(2b/5+4d/5-2f/5)/(b+2d-f)
=(2/5)×(b+2d-f)/(b+2d-f)
=2/5
应该是b+2d-f不等于0
a/b=c/d=e/f=2/5
则a=2b/5,c=2d/5,e=2f/5
(a+2c-e)/(b+2d-f)
=(2b/5+4d/5-2f/5)/(b+2d-f)
=(2/5)×(b+2d-f)/(b+2d-f)
=2/5