The speed equation when they walk towards each other is 

u + v = .      (the left side and the right side represent the relative speed for this case)

The speed equation when they walk in one direction is

u - v = .     (the left side and the right side represent the relative speed for this case)

Again,

u + v = 8,   (1)
u - v = 2.   (2)

Add the last two equations. You will get

2u = 10,   hence,  u = 5.

Then from  (1)  v = 8 - 5 = 3.


Answer.  5 m/sec  and  3  m/sec.