When Xiao Ming reads a book, he reads 25% of the whole book on the first day and 40% of the whole book on the second day. How much fewer pages are read on the first day than on the second day?
小明看一本书，第一天看了全书的25%，第二天看了全书的40%，第一天看的页数比第二天少多少．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) / (2/5)</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>