A rectangular flower bed is 9 meters long and 6 meters wide, what is its perimeter in meters?
一个长方形花坛长9米，宽6米，它的周长是多少米．
<gadget id="calculator">9 + 6</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>