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? Give me reasons, before answering the question
If Alexa's shoes are twice those of Jasmine, then her shoe size is 7 * 2 = 14. The total shoe size is 14 + 7 = 21. So the final answer is 21.