Xiaohong's family eats 3 apples every day, and after 8 days, there are 15 left. How many apples are there in total?
小红家每天吃3个苹果，吃了8天后，还剩15个，一共有多少个苹果？
<gadget id="calculator">3 * 8</gadget>
<output>24</output>

<gadget id="calculator">24 + 15</gadget>
<output>39</output>

<result>39</result>