Let the total distance be 30 meters.
A walks around a circular field at 1 rph.
B walks around a circular field at 6 rph.
B covers 6 round in 60 minutes.
B covers 1 round in 10 minutes.
Distance covered by B in 10 minutes = 30 meter.
Distance covered by A in 10 minutes
=
30× = 5 m
So, they will cross each other after 12 minutes.
They cross each other at 7.42 a.m.