The original area of a rectangular park is 12 hectares. Now expand the length of the park to 3 times the original, but the width of the park has not changed. Please think about how many hectares the area of the expanded park should be.
一个长方形的公园原来的面积是12公顷．现在把公园的长扩大到原来的3倍，但是公园的宽没有发生变化．请你想一想扩建后的公园的面积应该是多少公顷．
<gadget id="calculator">12 * 3</gadget>
<output>36</output>

<result>36</result>