The original price of "The Story of a Mathematician" is 25 yuan, and it is on sale with a 20% discount. How much is the current price?
《数学家的故事》原价25元，打八折出售，现价多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">25 * (4/5)</gadget>
<output>20</output>

<result>20</result>