The length of a rectangle is 8 meters and the width is 2 meters. What is the perimeter of the rectangle?
一个长方形的长是8米，宽是2米，这个长方形的周长是多少米．
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>