The price of a book after a 20% discount is 18.4 yuan. How much is the original price of this book?
一本书打八折后的售价是18.4元，这本书的原价是多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">18.4 / (4/5)</gadget>
<output>23</output>

<result>23</result>