If the length of a rectangle is 16 cm and the width is 9 cm, what is its perimeter in cm?
一个长方形的长是16厘米，宽是9厘米，它的周长是多少厘米．
<gadget id="calculator">16 + 9</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>