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

### Instruction:
Bob buys nose spray.  He buys 10 of them for a "buy one get one free" promotion.  They each cost $3.  How much does he pay?

### Response:
 บ็อบซื้อน้ำยาพ่นจมูก 10 ขวด ราคารวมทั้งหมด 10 x 3 = <<10*3=30>>30 ดอลลาร์