A kind of electric fan, the original price is 100 yuan, the current price is 80 yuan, how much is the price reduced?
一种电风扇，原价100元，现价80元，降价多少．
<gadget id="calculator">100 - 80</gadget>
<output>20</output>

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

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