2:30 is equal to 150 seconds
So the horse ran 2.25 miles in 150 seconds
To find the mile time in seconds divide 150 by 2.25 which equals 66.7sec per mile but it’s asking miles per minute and one mile is over a min so he runs Less than one mile per minute. So now you must divide 60 by 66.7 to find that he runs .89 miles per min.