you can figure this out by doing a proportion:
4.5 pages x pages
---------------- = ---------------
36 minutes 60 minutes(1 hr)
*makes sure that because they are giving you time in minutes that you convert the hour to minutes. also you need to always remember to line up the same factors like in this case line up the pages and the time.
36x = 4.5(60)
36x = 270
x = 270/36
x = 7.5 pages
hope this helps :)