There is a sidewalk with a width of 4 meters in Haibin Park, covering an area of 640 square meters. For convenience, the width of the road is increased to 12 meters, and the length remains unchanged. What is the area of the widened sidewalk in square meters?
海滨公园有一条宽4米的人行道，占地面积是640平方米，为了方便，道路宽度增加到12米，长不变．拓宽后人行道的面积是多少平方米？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">640 * 3</gadget>
<output>1_920</output>

<result>1_920</result>