Answer :
By simplifying the ration 90:3 you get 30:1. Cesar is reading 30 pages in 1 day. Dived the 450 by 30 to find how many days it will take to read while book. You should get 15. Then subtract 3 from 15 cause he was already read 3 day worth of pages. It will take Ceaser 12 days to finish the book.