The third grade students planted trees, a class of 50 people, with an average of 3 trees per person. There were 55 people in the second class, and a total of 165 trees were planted. How many trees does each third grader plant on average?
三年级同学植树，一班50人，平均每人植3棵．二班55人，共植树165棵．三年级平均每人植树多少棵？
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">150 + 165</gadget>
<output>315</output>

<gadget id="calculator">50 + 55</gadget>
<output>105</output>

<gadget id="calculator">315 / 105</gadget>
<output>3</output>

<result>3</result>