If the width of a rectangle is 8 cm and the length is twice the width, what is the perimeter of the rectangle in cm?
一个长方形的宽是8cm，长是宽的2倍，这个长方形的周长是多少cm．
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">16 + 8</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<result>48</result>