A rectangular picture frame is 12 decimeters long and 8 decimeters wide. Wrap it around its edge with a ribbon, how long is the ribbon at least?
一个长方形的镜框，长12分米，宽8分米．用彩带沿着它的边包一圈，至少需要多长的彩带？
<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<result>40</result>