The number of people in the chorus is three times that of the dance team. If you add 12 people to the dance team, the two teams will have the same number. How many people are there in the chorus?
合唱队的人数是舞蹈队人数的3倍，如果给舞蹈队增加12人，两队的人数就相等了，合唱队有多少人？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<result>18</result>