|1/21-1/20|﹢|1/21-1/22|+|1/23-1/22|+……+|1/30-1/29|解题方法
问题描述：
|1/21-1/20|﹢|1/21-1/22|+|1/23-1/22|+……+|1/30-1/29|解题方法
答
|1/21-1/20|﹢|1/21-1/22|+|1/23-1/22|+……+|1/30-1/29|
=1/20-1/21+1/21-1/22+1/22-1/23+……1/29-1/30
=1/20-1/30
=1/60