The question is asking how far the planes are right at the moment the jet plane caught up with the propeller plane, so they both are at the same distance from the starting point. So, we can just calculate the distance traveled for one of the planes.
So, lets calculate the distance traveled by the propeller plane.
It traveled at 200 miles per hour for 6 hours.
To find how far it traveled, multiply 200 by 6.
The answer is 1,200 miles.
