Shryia read a 481-page-long book cover to cover in a single session, at a constant rate. after reading for 1.5 hours, she had 403 pages left to read. how fast was shryia reading?

403 pages left, then she had read (481 - 403) = 78 pages in that 1.5 hours.
(78 pages / 1.5 hours) = (78 / 1.5) (pages/hours) = 52 pages per hour.
The whole book is 481 pages.
To read the whole book at the same rate will take (481 pages) / (52 page/hour) = (481 / 52) (hour) = 9.25 hours. 
9 hours 15 minutes