Zhang Cong read an extra-curricular book in the summer vacation. On the first day, he read 1/5 of the whole book, and the next day, he read 28 pages. At this point, the ratio of pages read to remaining pages is 5:6. How many pages are there in this book?

Solution: If you read 5x pages, there are 6x pages left, and the whole book is *** 1 1x pages; So there is an equation:

( 1 1/5)x+28=5x，

1 1x+ 140=25x

14x= 140

So x= 10, so this book has11×10 =110 pages.