A rectangular green lawn is 45 meters long and 20 meters wide. There is a square flowerbed with an area of 36 square meters in the middle. How big is the rectangular lawn?
一块长方形绿色草坪，长45米，宽20米，中间有一个面积是36平方米的正方形花圃，长方形的草地面积有多大？
<gadget id="calculator">45 * 20</gadget>
<output>900</output>

<gadget id="calculator">900 - 36</gadget>
<output>864</output>

<result>864</result>