If the length of a rectangle is 6 decimeters and the width is 4 decimeters, what is the perimeter of the rectangle?
一个长方形的长是6分米，宽是4分米，这个长方形的周长是多少分米．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

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

<result>20</result>