A group of elementary school students went to the park together. The adult ticket price in the park was 30 yuan per person, and the student ticket price was 12 yuan cheaper than the adult ticket price. If you buy a ticket and share 216 yuan, how many students are there in this group?
一群小学生一起去公园游玩，公园成人票价每人30元，学生票价比成人票价便宜12元．如果买门票共用去216元，这群学生一共有几人？
<gadget id="calculator">30 - 12</gadget>
<output>18</output>

<gadget id="calculator">216 / 18</gadget>
<output>12</output>

<result>12</result>