Dad wants to increase the length and width of the 6-meter-long and 4-meter-wide rectangular vegetable field at home by 2 meters. When building a fence around the vegetable field, how long should the fence be?
爸爸要把家中长6米，宽4米的长方形菜地的长和宽都增加2米，在菜地四周围上篱笆时，只需增加多长的篱笆就行？
<gadget id="calculator">6 + 2 + 4 + 2</gadget>
<output>14</output>

<gadget id="calculator">14 * 2</gadget>
<output>28</output>

<gadget id="calculator">4 + 2 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">28 - 20</gadget>
<output>8</output>

<result>8</result>