A rectangular flower pond is extended by 5 meters in width and 125 square meters in area, which just becomes a square flower pond. What is the area of the original rectangular flower pond in square meters?
一个长方形花池，宽延长5米，面积增加125平方米，正好变成正方形花池．原来长方形花池的面积是多少平方米？
<gadget id="calculator">125 / 5</gadget>
<output>25</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<gadget id="calculator">25 * 20</gadget>
<output>500</output>

<result>500</result>