If the length of a rectangle is 2 decimeters and the width is 8 centimeters, what is the perimeter?
一个长方形的长是2分米，宽是8厘米，周长是多少？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">20 + 8</gadget>
<output>28</output>

<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<result>56</result>