In March, the school helped the community carry out tree planting activities. 45 people from Class 1, Grade 5 planted 315 trees in total; 42 people from Class 2, Grade 5 planted 8 trees on average. How many trees did the two classes plant in total?
3月，学校帮助社区开展植树活动．五年级1班45人共植树315棵；五年级2班42人，平均每人植树8棵．两个班一共植树多少棵？
<gadget id="calculator">8 * 42</gadget>
<output>336</output>

<gadget id="calculator">315 + 336</gadget>
<output>651</output>

<result>651</result>