A rectangular vegetable field is 6 meters long and 4 meters wide, surrounded by a fence, how many meters is the minimum length of the fence?
一块长方形菜地，长6米，宽4米，四周围上篱笆，篱笆至少长多少米？
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

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

<result>20</result>