The number of apples is three times that of oranges. If you eat 2 apples and 1 orange every day, after a few days, there are 7 apples left, and the oranges are finished. How many apples are there?
苹果的个数是橘子的3倍，如果每天吃2个苹果、1个橘子，若干天后，苹果还剩下7个，橘子正好吃完，原来有苹果多少个？
<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">7 / 1</gadget>
<output>7</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>