A forest farm planted 240 willows in March, the number of poplars was twice that of willows, and the number of pine trees was the sum of the first two trees. How many pine trees were planted?
某林场三月份种柳树240棵，种杨树的棵数是柳树的2倍，种松树的棵数是前两种树的棵数之和，种松树多少棵？
<gadget id="calculator">240 * 2</gadget>
<output>480</output>

<gadget id="calculator">480 + 240</gadget>
<output>720</output>

<result>720</result>