(9又2/7+7又2/9)÷(5/7+5/9)

问题描述:

(9又2/7+7又2/9)÷(5/7+5/9)

﹙9又2/7+7又2/9﹚÷﹙5/7+5/9﹚
=﹙65/7+65/9﹚÷﹙5/7+5/9﹚
=13×﹙5/7+5/9﹚÷﹙5/7+5/9﹚
=13.