The area of a rectangular green space in Songbai Park is 216 square meters. Now we need to increase the length of the green space from the original 18 meters to 34 meters, and keep the width unchanged. How many square meters is the expanded green area?
松柏公园一块长方形绿地面积是216平方米，现在要把绿地的长从原来的18米增加到34米，宽保持不变．扩大后的绿地面积是多少平方米？
<gadget id="calculator">216 / 18</gadget>
<output>12</output>

<gadget id="calculator">12 * 34</gadget>
<output>408</output>

<result>408</result>