The current price of a brand of water dispenser is 400 yuan, which is 100 yuan lower than the original price, and how much is it lower than the original price
一种品牌的饮水机现售价400元，比原价降低了100元，比原价降低了多少
<gadget id="calculator">400 + 100</gadget>
<output>500</output>

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

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