Ms. Li and Ms. Yang from Yale School take 18 students to the amusement park. How many tickets do they need to buy?
雅乐学校李老师和杨老师带着18位同学去游乐园玩，需要买多少张票．
<gadget id="calculator">2 + 18</gadget>
<output>20</output>

<result>20</result>