Answer: Hello your question some data but i will provide a general solution based on the scope of your question making some suggestions as well
answer : Summation of displacements ( back and forth distance ) / Number of Runners
Step-by-step explanation:
Given that ; the aim of the race is to raise money
The number of miles/ distance covered will determine how much money that would be raised
Formula to resolve the problem = Summation of displacements ( back and forth distance ) / Number of Runners
Lets assume: ( example )
Distance between the Park and the City hall is = 6 miles
Number of runners = 4
Given that the runners Run from the Park to the City hall and then run back
Total miles covered by each runner = ( 6 + 6 )/ 4 = 12/4 = 3 miles