The formula for speed is distance over time which looks like this: d/v

So you basically take the distance which in this case is 2.5 miles and divided by the time which is 12 minutes. It'll look like this: (2.5 miles)/(12 minutes) which you get 2.083 miles per minute.

Since the question asks for miles per hour, you have to change minutes into hours.

To do that you need to know the ratio between minutes and hours. So every hour is equal to 60 minutes. The ratio is 1/60.

You need to multiply 2.083 by (1/60) which you get 0.0347. Looking at the units minutes get cancelled out and all that's left is miles per hour. So the answer is 0.0347 miles per hour.