A coat is sold for 80 yuan after a price reduction, which is 20 yuan cheaper than the original price. How much is the price reduction?
一件上衣降价后售80元，比原价便宜了20元，降价百分之几？
<gadget id="calculator">80 + 20</gadget>
<output>100</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>