The sixth-grade students planted trees. Generally, they planted 616 trees with the second class. There were 42 students in the first class, with an average of 8 trees per person, and 40 students in the second class. How many trees were planted per person on average?
六年级学生种树，一般和二班共种树616棵，一班有42人，平均每人种8棵，二班40人，平均每人种多少棵？
<gadget id="calculator">8 * 42</gadget>
<output>336</output>

<gadget id="calculator">616 - 336</gadget>
<output>280</output>

<gadget id="calculator">280 / 40</gadget>
<output>7</output>

<result>7</result>