What is the perimeter of a rectangle whose length is 10 meters and width is 3 meters?
长是10米，宽是3米的长方形，它的周长是多少米．
<gadget id="calculator">10 + 3</gadget>
<output>13</output>

<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<result>26</result>