The students went to the spring outing, 168 people from the second grade went, and twice as many people from the third grade as the second grade, how many people went to the two grades in total?
同学们去春游，二年级去了168人，三年级去的人数是二年级的2倍，两个年级一共去了多少人？
<gadget id="calculator">168 * 2</gadget>
<output>336</output>

<gadget id="calculator">336 + 168</gadget>
<output>504</output>

<result>504</result>