The first class planted 250 trees, 30 more than twice the number of the second class. How many trees were planted by the second class?
一班植树250棵，比二班的2倍多30棵，二班植树多少棵？
<gadget id="calculator">250 - 30</gadget>
<output>220</output>

<gadget id="calculator">220 / 2</gadget>
<output>110</output>

<result>110</result>