Question 327936
distance between P & q =120 km
speed = 80km/h
time taken = 120/80= 4/3 hours
..
return trip took 4/3 - 1/2 hour =5/6 hours
speed = 120/(5/6)
=120*6/5
=24*6
=144km/hour

Average speed = Total distance / total time

=120+120 / (4/3+5/6)
240/(8+5/6)
240*6/13
=1440/13
=110.7 km/hr average speed