(65/7+65/9)÷80/63＝65×(16/63)×(63/80)＝65/5＝13
解：(9又2/7+7又2/9)÷(5/7+5/9)=(65/7+65/9)÷[5(1/7+1/9)]=65(1/7+1/9)÷[5(1/7+1/9)]=65/5=13。😎😎😎😎😎😎😎😎😎😎
