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

### Instruction:
Mrs. Thompson bought 3 chickens for $3 each. She also bought a bag of potatoes. Mrs. Thompson paid $15 in total. How much did the potatoes cost?

### Response:
 ไก่ 3 ตัวรวมเป็นเงิน $3 x 3 = $<<3*3=9>>9
ดังนั้นมันฝรั่งคิดเป็นเงิน $15 - $9 = $<<15-9=6>>6