A certain brand of laundry detergent "does not increase the price if the quantity is increased", and the retail price is still 8 yuan after increasing the quantity by 25%. How much is it actually cheaper?
某品牌洗衣粉"加量不加价"，加量25%后零售价还是8元．实际便宜了多少元．
<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">8 / (5/4)</gadget>
<output>32/5 = around 6.4</output>

<gadget id="calculator">8 - (32/5)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>