After a price reduction of 100 yuan, a leather jacket sells for 400 yuan. How much is the price reduction?
一种皮衣降价100元后售价400元，降价了百分之几？
<gadget id="calculator">100 + 400</gadget>
<output>500</output>

<gadget id="calculator">100 / 500</gadget>
<output>1/5 = around 0.2</output>

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