Two teachers took a classmate to visit the park, and bought tickets for 23.1 yuan. It is known that one adult ticket is as expensive as three children's tickets. How much is one adult ticket?
两位老师带一名同学游公园，买门票共用去了23.1元，已知一张成人票和三张儿童票一样贵，一张成人票多少元？
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<gadget id="calculator">23.1 / 7</gadget>
<output>3.3</output>

<gadget id="calculator">3.3 * 3</gadget>
<output>9.9</output>

<result>9.9</result>