Grandpa Wang’s family has a rectangular vegetable field with a length of 8 meters and a width of 4 meters. How long should the fence be at least to surround the three sides of the vegetable field?
王爷爷家有一块长方形菜地的长是8米，宽是4米，在这块菜地的三边围上篱笆，至少需要多长的篱笆？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 + 8</gadget>
<output>16</output>

<result>16</result>