A rectangular park covers an area of 12 hectares. If the length of the rectangular park is tripled and the width remains the same, what is the area of the park after the expansion?
一个长方形公园占地12公顷，将这个长方形公园的长扩大到原来的3倍，宽不变，扩建后公园的面积是多少？
<gadget id="calculator">12 * 3</gadget>
<output>36</output>

<result>36</result>