能简便的简便3减2/5除以3/5 1/10除以（1/2+1/5） 2/15除以2/5+1/4 （35+5/7)除以5 3

3减2/5除以3/5
=3-2/5 X 5/3
=3-2/3
=9/3-2/3
=7/3
1/10除以（1/2+1/5）
=1/10X2+1/10X5
=1/5+1/2
=2/10+5/10
=7/10
2/15除以2/5+1/4
=2/15 X 5/2+1/4
=1/3+1/4
=4/12+3/12
=7/12
（35+5/7)除以5
=35X1/5+5/7X1/5
=7+1/7
=7又1/7
3/7除以7/8+4/7除7/8
=3/7X8/7+4/7X8/7
=（3/7+4/7）X8/7
=1X8/7
=8/7
7/9除以1/9—2/9除以1/9
=7/9 X9-2/9 X9
=(7/9-2/9)X9
=5/9 X 9
=5

1楼的第二题答案有误，嘻嘻
1/10除以（1/2+1/5）=1/10除以（7/10）=1/7