If the length of a rectangle is 28 cm and the width is 17 cm, what is its perimeter in cm?
一个长方形的长是28厘米，宽是17厘米，它的周长是多少厘米．
<gadget id="calculator">28 + 17</gadget>
<output>45</output>

<gadget id="calculator">45 * 2</gadget>
<output>90</output>

<result>90</result>