Given:
Fully charged scooter can last 45 minutes.
Total distance traveled on full charge = 39 km
Time of partial charge = 35 min
Distance covered after partial charge = 25 km
Formula used:
Average speed = total distance/total time
Calculation:
Total distance traveled = 39 + 25 = 64 km
Total time taken = 45 min + 35 min = 80 min
80 min = 4/3 hours
Average speed = 64/(4/3)
∴ Average speed of the scooter is 48 kmph