The floor of the classroom is rectangular, the length is 8 meters, and the width is 5 meters. What is the perimeter of the classroom floor in meters?
教室地面是长方形，长是8米，宽是5米，教室地面的周长是多少米？
<gadget id="calculator">8 + 5</gadget>
<output>13</output>

<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<result>26</result>