Each of the fourth-grade students planted 12 trees. A total of 240 pine trees and 228 poplar trees were planted. How many fourth-grade students participated in the tree planting?
四年级学生每人植树12棵，共植了240棵松树，228棵杨树，四年级有多少名学生参加了植树？
<gadget id="calculator">240 + 228</gadget>
<output>468</output>

<gadget id="calculator">468 / 12</gadget>
<output>39</output>

<result>39</result>