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

### Instruction:
Jasmine and her older sister Alexa went to the store to buy shoes. Alexa's shoes are twice as big as Jasmine's shoes. If Jasmine's shoe size is 7, what's the combined shoe size for both of them?

### Response:
 ถ้ารองเท้าของอเล็กซาใหญ่กว่าของจาสมินสองเท่า แสดงว่าขนาดรองเท้าของเธอคือ 7 * 2 = <<7*2=14>>14
ขนาดรองเท้ารวมกันคือ 14 + 7 = <<14+7=21>>21