The perimeter of a rectangular playground is 420 meters, its length is 110 meters, and its width is in meters.
一个长方形的操场周长是420米，它的长是110米，宽是多少米．
<gadget id="calculator">420 / 2</gadget>
<output>210</output>

<gadget id="calculator">210 - 110</gadget>
<output>100</output>

<result>100</result>