After the side length of a square playground is increased by 1/4, the perimeter of the new playground is 500 meters. What is the side length of the original playground? (solution by equation)
一个正方形操场的边长增加它的四分之一后，得到的新操场的周长是500米，原操场的边长是多少？(用方程解)
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) * 4</gadget>
<output>5</output>

<gadget id="calculator">500 / 5</gadget>
<output>100</output>

<result>100</result>