A rectangle is 6 decimeters wide and twice as long as it is wide. What is the perimeter of the rectangle?
一个长方形宽6分米，长是宽的2倍，这个长方形的周长是多少分米．
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<result>36</result>