Students do exercises, 15 people stand in each row, exactly 12 rows. How many rows can you stand if there are 9 people in each row?
同学们做操，每行站15人，正好站12行．如果每行站9人，可以站多少行？
<gadget id="calculator">15 * 12</gadget>
<output>180</output>

<gadget id="calculator">180 / 9</gadget>
<output>20</output>

<result>20</result>