Answers

2014-09-20T16:17:04+05:30
Time taken to travel 20 km at 60km/hr=20/60=0.33hr
time taken to travel nxt 20 km at 80km/hr=20/80=0.25hr
avg speed=total distance travelled / total time taken=40/0.58=68.96km/hr
                                                                                                ≈69km/hr
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2014-09-20T16:22:40+05:30
avg speed=total distance travelled / total time taken=40/0.58=68.96km/hr=69.00 km/hr
                                                                                               
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