The hardcover price of a book is 15 yuan, and the paperback price is 12 yuan. How much is the paperback price cheaper than the hardcover one?
一本书精装定价15元，平装定价12元，平装的价格比精装的便宜百分之几？
<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<gadget id="calculator">3 / 15</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>