rectangular flower bed is 6 meters long and twice its width, what is the perimeter of the flower bed in meters?
一个长方形花坛长6米，是宽的2倍，这个花坛的周长是多少米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

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

<result>18</result>