A kind of clothing is engaged in promotional activities, and the price is reduced by 10%, and the mall returns 5% of the selling price in cash. If you buy a piece of clothing like this, it is equivalent to reducing the price.
一种衣服搞促销活动，降价10%出售，商场又返还售价5%的现金．若买一件这样的衣服，相当于降价多少．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 - (1/20)</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">(9/10) * (19/20)</gadget>
<output>171/200 = around 0.855</output>

<gadget id="calculator">1 - (171/200)</gadget>
<output>29/200 = around 0.145</output>

<result>29/200 = around 0.145</result>