Ming bought a book with a 20% discount, which is 6 yuan cheaper than the original price. What is the original price of this book?
明买了一件打八折的书，比原价便宜了6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">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">6 / (1/5)</gadget>
<output>30</output>

<result>30</result>