1+1/3-7/12+9/20-11/30+13/42=
问题描述：
1+1/3-7/12+9/20-11/30+13/42=
答
1+1/3-7/12+9/20-11/30+13/42
=1+1/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7
=1+1/7
=8/7