A rectangular flowerbed is 60 meters long and 30 meters wide. How long is the fence needed to surround the flowerbed?
一个长方形的花圃，长60米，宽30米，要在花圃周围围一圈篱笆，需要多长的篱笆？
<gadget id="calculator">60 + 30</gadget>
<output>90</output>

<gadget id="calculator">2 * 90</gadget>
<output>180</output>

<result>180</result>