A rectangular vegetable field is 7 meters long and 4 meters wide. How many meters should the fence be at least?
一块长方形菜地，长7米，宽4米．四面围上篱笆，篱笆至少要多少米？
<gadget id="calculator">7 + 4</gadget>
<output>11</output>

<gadget id="calculator">11 * 2</gadget>
<output>22</output>

<result>22</result>