The third-grade students planted 9 rows of trees in 3 hours, with 24 trees in each row. How many trees do third graders plant per hour?
三年级同学3小时共植树9排，每排24棵．三年级同学每小时植树多少棵？
<gadget id="calculator">24 / 3</gadget>
<output>8</output>

<gadget id="calculator">9 * 8</gadget>
<output>72</output>

<result>72</result>