A certain commodity is sold at the original price, and the profit per piece is 50% of the cost, and then it is sold at a 20% discount. As a result, the number of pieces sold per day has increased by 2.5 times compared with that before the price reduction, and the total profit of this commodity has increased by 100% compared with that before the price reduction. Several? How many
某商品按原价出售每件利润为成本的50%，后来打八折出售，结果每天售出的件数比降价前增加了2.5倍，每天经营这种商品的总利润比降价前增加了百分之几？多少
<gadget id="calculator">0.7 - 0.5</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 / 0.5</gadget>
<output>0.4</output>

<result>0.4</result>