1.05×（3.8-0.8）÷9.3=1.05×3÷9.3=3.15÷9.3=315/930=21/62
1.05×(3.8-0.8)÷9.3=1.05×3÷9.3=3.15÷9.3=21/62 ≈ 0.3387
1.05×（3.8-0.8）÷9.3=1.05×3÷9.3=3.15÷9.3≈0.339
=1.05×3÷9.3=1.05÷3.1=105／310
