A vegetable field is 18 meters long and 6 meters less wide than long. How many meters of fence is needed to build a fence around the vegetable field?
有一块菜地长18米，宽比长少6米．要在菜地的四周围上篱笆，需要篱笆多少米？
<gadget id="calculator">18 - 6</gadget>
<output>12</output>

<gadget id="calculator">18 + 12</gadget>
<output>30</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>