The original price of a book is 19.8 yuan, and now the price has been reduced by 15%. How much should I pay for this book now?
一种书原价为19.8元，现在降价15%，现在买这本书应付多少钱？
<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">19.8 * (17/20)</gadget>
<output>16.83</output>

<result>16.83</result>