A rectangular flower bed is 6 meters long and 3 meters wide, what is its perimeter?
一个长方形花坛的长是6米，宽是3米，它的周长是多少．
<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>