On a plan with a scale of 1:500, the perimeter of a rectangular classroom is 12 cm, and the ratio of length to width is 2:1. Find the actual area of this classroom.
在一幅比例尺为1：500的平面图上，量得一间长方形教室的周长是12厘米，长与宽的比是2：1．求这间教室的实际面积．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">12 / 2 / 3</gadget>
<output>2</output>

<gadget id="calculator">1 / 500</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">12 / 2 / 3 / (1/500) / 100</gadget>
<output>10</output>

<gadget id="calculator">2 * 10 * 10</gadget>
<output>200</output>

<result>200</result>