A rectangular mirror is 4 meters long and 2 meters wide, what is its perimeter in meters?
一面长方形镜子，长4米，宽2米，那么它的周长是多少米．
<gadget id="calculator">4 + 2</gadget>
<output>6</output>

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

<result>12</result>