Li Ying reads a book. On the first day, she reads 1/3 of the whole book, and on the second day, she reads 18 pages more than 25% of the whole book. At this time, the ratio of the number of pages read to the number of pages not read is 3: 1. How many pages are there in this book?
李英读一本书，第一天读了全书的(1/3)，第二天读的比全书的25%还多18页，这时读了的页数和没读的比是3：1，这本书共有多少页？
<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">3 + 1</gadget>
<output>4</output>

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

<gadget id="calculator">1 - (1/3) - (1/4) - (1/4)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">18 / (1/6)</gadget>
<output>108</output>

<result>108</result>