Final answer:
Gregg can drive 225 miles in 5 hours.
Step-by-step explanation:
To find out how far Gregg can drive in 5 hours, we can use the concept of average speed. Average speed is calculated by dividing the total distance traveled by the total time taken. In this case, Gregg drove 135 miles in 3 hours, so his average speed is 135/3 = 45 miles per hour. To determine how far Gregg can drive in 5 hours, we multiply his average speed by the total time: 45 * 5 = 225 miles.