The floor of the classroom is a rectangle with a length of 9 meters and a width of 7 meters. What is its perimeter in meters?
教室的地面是长方形，长9米，宽7米，它的周长是多少米？
<gadget id="calculator">9 + 7</gadget>
<output>16</output>

<gadget id="calculator">16 * 2</gadget>
<output>32</output>

<result>32</result>