Xiao Ming took 20 yuan to Xinhua Bookstore in Leling to buy extra-curricular reading guidance books for classic recitation. The salesperson aunt gave the wrong money and gave 15.12 yuan more. The result was a total of 18.32 yuan. How much is the price of this book?
小明带20元钱去乐陵新华书店购买经典诵读课外阅读辅导书，售货员阿姨找错了钱，多找给了15.12元，结果共找回18.32元．这本书的价钱是多少元？
<gadget id="calculator">18.32 - 15.12</gadget>
<output>3.2</output>

<gadget id="calculator">20 - 3.2</gadget>
<output>16.8</output>

<result>16.8</result>