Use a 24-meter-long rope to enclose a rectangular activity field (one side is close to the wall), what is the maximum area?
用24米长的绳子围一个长方形的活动场地(其中一边靠墙)，面积最大是多少？
<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>