Question 1072723
Let n be the speed of the first group. Then the speed of the second group would be n+.5. So:
1050/(n+n+.5)=200
400n+100=1050
400n=950
n=2.375 
n+.5=2.875
The first group travels at 2.375 mph; the second group travels at 2.875 mph. ☺☺☺☺