Mrs. arshad gave her class 12 minutes to read independently. sadia read 5 1/2 pages in that time how many pages will she read in one hour? at that rate how many pages could sadia read in 3 hours at this rate ? justify how you determine how many pages sadia could read in 3 hours

So 5 1/2 pages in 12 minutes
rewrite as eleven/2
Make a proportion
pages over minutes = pages over minutes
in an hour, there are 60 minutes
11/2 / 12 = x / 60
cross multiply 
(11/2 * 60) = 12x
330 = 12x 
divide both sides by 12
27.5 = x

She will read 27.5 pages in an hour.

How many pages in 3 hours?
that is 60 * 3 minutes 
180 minutes
Use the proportion of pages/minutes = pages/minutes
plug in what you are given

11/2 / 12 = x / 180
Cross multiply
(11/2 * 180) = 12x
990 = 12x
divide both sides by 12
82.5 = x

She will read 82.5, or 82 1/2, pages in 3 hours (or 180 minutes ;) )

Hope this helps