=12.5/3.6-7*0.4/0.4/9+8.3/3.6=(12.5-2.8+8.3)/3.6=18/3.6=5
=20.8÷3.6-7÷9=（20.8÷0.4）÷9-7÷9=52÷9-7÷9=（52-7）÷9=45÷9=5
(12.5+8.3-2.8)/3.6=5
