1/5 of a book was read on the first day. The ratio of reading on the second day to reading on the first day was 5:4. There were 66 pages left unread. How many pages were there in the book?

If the book has x pages: I read 1/5x page on the first day I read (5/6)x pages the next day, where 5/6x means that the number of pages read on the first day accounts for 5/6 of the number of pages read on the second day. The remaining pages are x - 1/5x - (5/6)x = 66 pages According to the above equations, a set of linear equations with two variables can be listed: 1/5x + (5/6)x = 66 Solution:x = 460 Therefore, the book had 460 pages.