A book is reduced from 30 yuan to 24 yuan. How much is the price reduction of this book?
一本书，由原来30元降到24元，这本书降价百分之几？
<gadget id="calculator">30 - 24</gadget>
<output>6</output>

<gadget id="calculator">6 / 30</gadget>
<output>1/5 = around 0.2</output>

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