piece of rectangular glass is 6 decimeters long and twice as long as it is wide. If wooden strips are placed around it, how many decimeters are needed for the wooden strips?
一块长方形玻璃，长是6分米，长是宽的2倍，在它的四周镶上木条，需要木条多少分米？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>