Answer:

Paul will catch Fred after
at a distance
.
Explanation:
Distance is represented by
and the time is represented by
. Here after
hours(when Fred started) the distance covered by Fred and Paul is same that is
.
For Fred:
time=

distance=

Speed


Paul:
Since Fred started 30 minutes earlier, so Paul's travel time will be 30 minutes less than that of Fred.
Time

Speed

Distance


Hence system of equation

Solution of this system of equations gives the time, when Paul will catch Fred and distance covered by each of them.

Time taken by Paul

Hence Paul will catch Fred after
at a distance
.