Answer:
Each person runs 3 miles in a relay race.
Explanation:
Given:
Distance of Relay race m = 12 miles.
The expression m divided by 4 is the distance each person runs in a relay race that is m miles.
Each person runs in relay race =

Now given the total distance of the relay race is 12 miles.
i.e. value of m = 12 miles
Now substituting the value of m in above equation we get;
Each person runs in relay race =

Hence each person runs 3 miles in a relay race.