The original price of a dictionary is 19.50 yuan, how much is it after a 20% discount.
一本字典原价是19.50元，打八折后是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">19.5 * (4/5)</gadget>
<output>15.6</output>

<result>15.6</result>