A book is 16 yuan after a 20% discount. What is the original price?
一本书打八折后是16元，原价是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">16 / (4/5)</gadget>
<output>20</output>

<result>20</result>