The perimeter of a rectangle is 36 meters. It is known that the length is twice the width. What is the area of the rectangle?
一个长方形的周长是36米，已知长是宽的2倍，这个长方形的面积是多少．
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">36 / 2 / 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>