Answer:
50 seconds
Explanation:
Let x be the distance ( in meters ) from kyle to the point where they meet.
Since,

For kyle,
Distance = x,
Speed = 3 m/s
So, time taken by Kyle =

Now, for Michael,
Distance = (x + 50) ( Because Kyle is 50 meters ahead of Michael )
Speed = 4 m/s
So, time taken by Michael =

When they meet each other,



Hence, the time after which they meet =
= 50 seconds