The average speed is calculated by dividing the total distance traveled by the total time spent for the travel. It is given in this item that the distance covered in the one-way trip is 145 miles. Multiplying this by 2 will give us the total distance covered equal to 290 miles. To calculate for the average speed, we divide this by 5 hours.
This is as shown below,
Average speed = (290 miles/5 hours) = 58 miles per hour
ANSWER: 58 mph