On Arbor Day, Teacher Wang led the students to plant trees. She divided the students into 3 groups with 20 people in each group. A total of 240 trees are to be planted, how many trees are planted per person on average?
植树节这天，王老师带领同学们去植树．她把同学们分成3个小组，每个小组20人．共要植树240棵，平均每人植树多少棵？
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">240 / 60</gadget>
<output>4</output>

<result>4</result>