A merchant marked a piece of clothing at 580 yuan. After being identified by anti-counterfeiting personnel, it was reduced to 100 yuan and sold, and it could still earn 25%. If it was sold at the original price, how much could it earn per piece.
某商家把一件衣服标价为580元，经打假人员鉴别，降至100元一件出售，仍可赚25%，如按原标价出售，则每件可赚多少元．
<gadget id="calculator">25 / 100</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">100 / (5/4)</gadget>
<output>80</output>

<gadget id="calculator">580 - 80</gadget>
<output>500</output>

<result>500</result>