The perimeter of a rectangle is 36 meters, what is the maximum area in square meters?
一个长方形的周长是36米，它的面积最大是多少平方米？
<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>