Uncle Wang has a rectangular vegetable garden with a length of 20 meters and a width of 12 meters. Now it is necessary to fence around it. How long is the fence?
王大伯有一块长方形的菜园，长20米，宽12米，现在要将它的四周围上篱笆，篱笆长多少米？
<gadget id="calculator">20 + 12</gadget>
<output>32</output>

<gadget id="calculator">32 * 2</gadget>
<output>64</output>

<result>64</result>