Hello Mirusha,
Let's break this down:
- "subtract 9 from 18" means 18 - 9
- "then divide by 3" means you divide the previous step by 3: (18-9) ÷ 3 = 9÷3
So we wrote the sentence as the following expression: (18-9) ÷ 3 which equals 9 ÷ 3 and the answer is 3