若x/3=y/4=z/5，则-x+y/x+2y+3z=_．

题目

若

x

3

=

y

4

=

z

5

答案

设

x

3

=

y

4

=

z

5

=k，
则x=3k，y=4k，z=5k，
所以

-x+y

x+2y+3z

=

-3k+4k

3k+2×4k+3×5k

=

1

26

．
故答案为：

1

26

．