A certain brand of laundry detergent is engaged in promotional activities. After increasing the quantity by 25%, it still sells for 10 yuan, which is how much less than the original price.
某品牌洗衣液搞促销活动，加量25%后还是卖10元，比原价少多少元．
<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">10 * (5/4)</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">(25/2) - 10</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>