The floor of the classroom is 8 meters long and 7 meters wide, what is its perimeter in meters?
教室地面长8米，宽7米，它的周长是多少米？
<gadget id="calculator">8 + 7</gadget>
<output>15</output>

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

<result>30</result>