A rectangular pool is 5 meters long and 3 meters wide, what is its perimeter?
一个长方形水池，长5米，宽3米，它的周长是多少米？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>