Respuesta :

Since he runs 9/4 (2.25) of a mile in 15 minutes, divide 9/4 by 15 in order to find the rate runs at.

You should get 0.15, now multiply it by 60 ( 60 min. = 1 hour) in order to find his mile rate in one hour. 

He runs 9 miles in an hour.
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