Xiao Ming reads a book. I read the whole book (1/3) for the first time, and read 25% of the whole book the next day, and there are 125 pages left. How many pages are there in this book?
小明看一本书．第一看了全书的(1/3)，第二天看了全书的25%，还有125页没看，这本书一共多少页？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">1 - (1/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">125 / (5/12)</gadget>
<output>300</output>

<result>300</result>