A book is priced at 36 yuan after a 20% discount. What is the original price of this book?
一本书打八折后售价是36元，这本书原价是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">36 / (4/5)</gadget>
<output>45</output>

<result>45</result>