If the perimeter of a rectangle is 60 meters and the length is twice the width, find the area of the rectangle.
一个长方形的周长是60米，长是宽的2倍，求长方形的面积．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<result>200</result>