-|-2/3-(+2/3)|-|(-1/5)+(-2/5)| |4/7-2/5|-|3/5-7/9|+|2/9-3/7|

问题描述:

-|-2/3-(+2/3)|-|(-1/5)+(-2/5)| |4/7-2/5|-|3/5-7/9|+|2/9-3/7|

1:原式=-4/3-3/5=-29/15
2:原式=6/35-8/45+13/63
=1/5