Xiaojun bought a book for 17 yuan, 15% cheaper than before. How much is the original price of this book?
小军花17元买了一本书，比原来便宜15%．这本书原价多少元？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">17 / (17/20)</gadget>
<output>20</output>

<result>20</result>