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

### Instruction:
John goes to the store to buy Slurpees and gives them $20.  Slurpees cost $2 each and he got $8 in change.  How many Slurpees did he buy?

### Response:
 เขาใช้เงิน 20-8=12 บาทสำหรับซื้อสลัด
ดังนั้นเขาได้ซื้อสลัด 12/2=6 แก้ว