Below is an instruction that describes a task. Write a response that appropriately completes the request in Thai. Please answer in Thai.

### Instruction:
Each class uses 200 sheets of paper per day. The school uses a total of 9000 sheets of paper every week. If there are 5 days of school days, how many classes are there in the school?

### Response:
 แต่ละชั้นใช้กระดาษ 200 x 5 = <<200*5=1000>>1000 แผ่นต่อสัปดาห์
ดังนั้น โรงเรียนมีชั้นเรียนทั้งหมด 9000/1000 = <<9000/1000=9>>9 ชั้น