A park is a rectangle with an area of 12 hectares. In order to further afforest the park, the length of this rectangular park needs to be expanded to four times the original size. What is the area of the park after the expansion?
某公园是一个长方形，占地12公顷．为了进一步绿化公园，需要将这个长方形公园的长扩大到原来的4倍，扩建后公园的面积是多少？
<gadget id="calculator">12 * 4</gadget>
<output>48</output>

<result>48</result>