After reading 5/8 of a book, 168 pages are left. How many pages are there in all in a book ?

after reading 5/8 of a book, 168 pages are left means

3/8 of book = 168 pages

1/8 of book = 168/3 =56 pages

8/8 =1 full book contains = 56 x 8 = 448 pages

Thus, 448 pages are there in the book