rectangular vegetable field in the school is 9 meters long and 7 meters wide. It is necessary to build a fence around the vegetable field. What is the minimum length of the fence?
学校的一块长方形菜地长9米，宽7米，要在菜地的四周围上篱笆，篱笆至少要挖多长？
<gadget id="calculator">9 + 7</gadget>
<output>16</output>

<gadget id="calculator">16 * 2</gadget>
<output>32</output>

<result>32</result>