How long before fred and wilma meet on the other side of a 400m track running in opposite directions?

Question

given: fred runs 17 meters every two seconds, Wilma runs 6 yards per second, answer to the nearest second

Answer 1

the relative speed will get added up as they are running in oppositedirections
distance=400m
speed=8.5+6*0.9144
=8.5+5.4864
=13.9864
time=distance/speed
=400/13.9864
=28.6sec
=29 sec

Answer 2

The sum of the distances that they run must equal 400 m and they run for the same amount of time.

Answer 3

6 yds/sec/1.09yd/m=5.49m/sec
17m/2sec=8.5m/s
they are closing at 8.5+5.49=13.99m/s
they will close 400m in 400m/13.99m/s=28.6 sec or 29 sec