If Ben traveled 150 miles in 3 hours what was his average. So to find the average speed never use the formula of the averages but try to find the total distance covered and the total time taken. If you have the average and initial speed.
The Average Speed of an object is a measure of the distance covered by that object in a set period of time.
It is the distance covered divided by time. To get distance D D multiply speed times the amount of time. Plug the time into the formula. Furthermore this time is elapsed so as to cover that particular distance.