Do you see a pattern in the given information?
3 pages in 13 min
9 pages in 39 min
15 pages in 65 min
the rate of pages per min is constant
3/13 = 9/39 = 15/65
the Question is asking for time.. So the we need the rate as min per page 13/3 so when multiplied by the number of pages it cancels to give minutes.
Units cancel out just like numbers do so you know that the problem is set up correctly.
