To build a chicken coop against the wall, it is required to be 8 meters long and 12 meters wide. How many meters is the fence of the chicken coop in the case of the most economical material?
靠墙建一个鸡舍，要求长8米，宽12米，在最省料的情况下，鸡舍的围栏长多少米？
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">12 + 16</gadget>
<output>28</output>

<result>28</result>