Answer: Hello mate!
We want to find the average speed while the trucker was on the road, this average velocity is equal to the total distance divided by the total amount of time in the road.
The total distance is 2865 miles, and we know that the entire trip required 77 hours and 30 minutes, but there are 16 h and 30 min where spend sleeping and 3h 40min was used for meals, then the total amount of time in the road is:
77 hours and 30 mins - 3 hours and 40 mins - 16 hours and 30 mins
= 57 hours and 20 minutes of time in the road.
where we can write this in hours as 57.33 hours.
then the velocity in miles per hour is:
2856mi/57.33h = 49.8 miles per hour.