For a square, the side length is increased by 5 meters, and the area is increased by 125 square meters. What is the original area of this square in square meters?
一个正方形，边长增加5米，面积增加125平方米，求原来这个正方形面积是多少平方米？
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">125 - 25</gadget>
<output>100</output>

<gadget id="calculator">100 / 2 / 5</gadget>
<output>10</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<result>100</result>