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

### Instruction:
John buys 1000 balloons.  Each balloon holds 10 liters of air.  If he buys 500-liter tanks of gas, how many tanks does he need to buy to fill all the balloons?

### Response:
 เขาต้องการ 1000*10=<<1000*10=10000>>10000 ลิตรของแก๊ส
ดังนั้นเขาต้องซื้อ 10000/500=<<10000/500=20>>20 ถัง