There are 240 pine trees planted in a certain park, 30 fewer than three times as many willows, and willows are half as many as poplars. How many poplar trees are planted in the park?
某公园共种240棵松树，比柳树的3倍少30棵，柳树是杨树的一半．公园种杨树多少棵？
<gadget id="calculator">240 + 30</gadget>
<output>270</output>

<gadget id="calculator">270 / 3</gadget>
<output>90</output>

<gadget id="calculator">90 * 2</gadget>
<output>180</output>

<result>180</result>