Uncle Li built a rectangular chicken coop with a fence against the wall. The chicken coop is 9 meters long and 6 meters wide. How many meters is the minimum length of the fence?
李叔叔靠墙用篱笆围了一个长方形鸡舍，鸡舍长9米，宽6米，算一算篱笆至少长多少米？
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">9 + 12</gadget>
<output>21</output>

<result>21</result>