If the length of a rectangle increases by 1/5 and the width decreases by 1/5, the area decreases by 20 square centimeters. What is the area of the original rectangle in square centimeters?
一个长方形，长增加(1/5)，宽减少(1/5)，面积就减少20平方厘米，原来长方形的面积是多少平方厘米？
<gadget id="calculator">25 * 20</gadget>
<output>500</output>

<result>500</result>