Alex is planning a road trip and needs to calculate the average distance he will travel each day. He plans to drive to four different cities over four days. On the first day, he will drive 120 miles, on the second day 150 miles, on the third day 180 miles, and on the fourth day 200 miles. What is the average distance Alex will travel per day? Let's think step by step and output the final answer within \boxed{}.
user