School organization queue training. If there are 18 people standing in each row, there are exactly 15 rows standing. How many rows can you stand if there are 9 people in each row?
学校组织队列训练．如果每行站18人，正好站15行．如果每行站9人，可以站多少行？
<gadget id="calculator">15 / 9</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">18 * (5/3)</gadget>
<output>30</output>

<result>30</result>