The sixth grade students of Lixin Primary School participated in the tree planting activity. There are 40 people in the first class, and each person plants 4 trees on average. The second class has 38 people, and each person plants 5 trees on average. How many more trees are planted in the second class than in the first class?
立新小学六年级学生参加植树活动．一班有40人，平均每人植树4棵，二班有38人，平均每人植树5棵，二班比一班多植树多少棵？
<gadget id="calculator">38 * 5</gadget>
<output>190</output>

<gadget id="calculator">40 * 4</gadget>
<output>160</output>

<gadget id="calculator">190 - 160</gadget>
<output>30</output>

<result>30</result>