Average speed is the total distance traveled divided by the total time taken. The formula is:
Average Speed = Total Distance / Total Time
It's important to note this is different from taking the average of the speeds of each leg of the journey, especially if the time spent in each leg is different.

Speed is a scalar quantity—it only has magnitude (e.g., 60 mph). Velocity is a vector quantity, meaning it has both magnitude and direction (e.g., 60 mph North). For a round trip, your average speed would be positive, but your average velocity would be zero because your starting and ending positions are the same, resulting in zero displacement.