The store sells a product at a price of 16 yuan, and loses 20%, so how much is the loss.
商店以16元的价钱卖出一件商品，亏了20%，那么亏了多少元．
<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">16 / (4/5)</gadget>
<output>20</output>

<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<result>4</result>