The unknowns are the number of shoppers per minute, corresponding to the letters on the diagram

If we set traffic in = traffic out at each intersection, we get the following system of equations

In = OutEquation
Intersection near Present Location:40 + x + s = zx - z + s = -40
Intersection near Burger King:40 + t = y + sy + s - t = 40
Intersection near Apple Computer:60 + z = 50 + t z - t = -10

and the general solution is:

 


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