÷ → + → ×
× → + → ÷
+ → × → ÷
+ → ÷ →×
(7/9÷2/9+2/5)×5/6
7/9÷(2/9+2/5×5/6)
7/9÷[(2/9+2/5)×5/6]
7/9÷(2/9+2/5)×5/6
[7/9÷(2/9+2/5)]×5/6