Xiao Ming reads a story book. He reads 25% of the whole book on the first day, and reads 24 pages on the second day. The ratio of the number of pages read in two days to the number of remaining pages is 2:5. How many pages are there in this book? ?
小明看一本故事书，第一天看了全书的25%，第二天看了24页，两天看了的页数与剩下页数的比是2：5，这本书共有多少页？
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

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

<gadget id="calculator">(2/7) - (1/4)</gadget>
<output>1/28 = around 0.035714</output>

<gadget id="calculator">24 / (1/28)</gadget>
<output>672</output>

<result>672</result>