A rectangle is 4 decimeters wide and its width is half its length. What is the perimeter of this rectangle?
一个长方形宽4分米，宽是长的一半，这个长方形的周长是多少．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">4 + 8</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<result>24</result>