Uncle Wang surrounded a rectangular sheepfold with a length of 15 meters and a width of 6 meters against a wall. What is the minimum circumference of the sheepfold?
王大叔靠一面墙围了一个长15米，宽6米的长方形羊圈，羊圈的周长至少是多少米？
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 15</gadget>
<output>27</output>

<result>27</result>