The store sells a piece of clothing for 60 yuan, which is 20% cheaper than the original price, and how much cheaper than the original price.
商店卖一件衣服售价为60元，比原价便宜20%，比原来便宜多少元．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">60 / (4/5)</gadget>
<output>75</output>

<gadget id="calculator">75 * (1/5)</gadget>
<output>15</output>

<result>15</result>