For a book for students, the wholesaler wholesales it to the retailer at 25% off the original price, and the retailer wholesales it to the students at 90% of the original price. As a result, the retailer makes a profit of 1.5 yuan per book. Please calculate the price of this book.
一种学生用书，批发商按原定价七五折批发給零售商，零售商又按原价的90%批发给学生，结果每本书零售商获利1.5元．请计算这本书的定价．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(9/10) - (3/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1.5 / (3/20)</gadget>
<output>10</output>

<result>10</result>