Li Ming finished reading a book in two days. The ratio of the number of pages he read on the first day to the number of pages in the book was 1:4, and he read 120 pages more on the second day than on the first day. How many pages in this book?
李明两天读完一本书，第一天读的页数与全书页数的比是1：4，第二天比第一天多读120页，这本书共有多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4) - (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">120 / (1/2)</gadget>
<output>240</output>

<result>240</result>