The car has changed its speed during its travel.
Otherwise, if it takes 1/2 hrs to travel 2/7 of journey,
it will take 1/4 hr to travel 1/7 of journey (divide by 2); or
5/4 hr to travel the remaining 5/7 of journey (times 5).
But the car took 3 hrs to travel the remaining 5/7 of journey.
Average speed = Total distance/Total time
Given that the van kept its speed constant at 70km/h, in that last 3 hr, it travelled 70×3=210km.
Car has reached Town Q and distance it travelled is 210+65 = 275km –> 5/7 of journey
55km <– 1/7 of journey
385km <– 7/7 of journey
Average speed = Total distance/Total time = 385 / (0.5+3) = 110km/h#