Two classes of the fifth grade participated in the tree planting activity. There were 37 students in the first class, and a total of 331 trees were planted; 35 students in the second class, with an average of 7 trees per person. How many trees does the fifth grader plant on average?
五年级两个班参加植树活动，一班37人，共植树331棵；二班35人，平均每人植树7棵．五年级平均每人植树多少棵？
<gadget id="calculator">7 * 35</gadget>
<output>245</output>

<gadget id="calculator">245 + 331</gadget>
<output>576</output>

<gadget id="calculator">37 + 35</gadget>
<output>72</output>

<gadget id="calculator">576 / 72</gadget>
<output>8</output>

<result>8</result>