There are 21 apples, 3 times more than oranges, how many oranges are there, and how many are the correct ones?
苹果有21个，比桔子的3倍还多3个，桔子有多少个，列式正确的是多少
<gadget id="calculator">21 - 3</gadget>
<output>18</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<result>6</result>