﹙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.