Two classes in the fifth grade participated in tree planting. The first class planted 240 trees, 60 more than three times the number planted by the second class. How many trees were planted by the second class?
五年级两个班参加植树，一班植树240棵，比二班植的3倍还多60棵，二班植树多少棵？
<gadget id="calculator">240 - 60</gadget>
<output>180</output>

<gadget id="calculator">180 / 3</gadget>
<output>60</output>

<result>60</result>