An 850 yuan coat, how much is it after a 20% discount.
一件850元的上衣，打八折后是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">850 * (4/5)</gadget>
<output>680</output>

<result>680</result>