The length of a rectangle is 8.5 decimeters, which is 4 decimeters more than the width. What is the perimeter of this rectangle?
一个长方形的长是8.5分米，比宽多4分米，这个长方形的周长是多少分米？
<gadget id="calculator">8.5 - 4</gadget>
<output>4.5</output>

<gadget id="calculator">4.5 + 8.5</gadget>
<output>13</output>

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

<result>26</result>