You do 1/2x60=30 because you can find out how many pages he can read per hour. Which is 30 pages per hour. So Alex can read 30 pages per hour and Sammie can only read 25 pages per hour. To find how many pages he reads faster per hour, you have to take 30 and subtract it by 25 to get 5 extra pages. So Alex reads 5 pages faster per hour. In the end, Alex reads faster than Sammie by 5 more pages per hour.
