A car travels at a constant speed of 60 miles per hour on a highway. After 2 hours, it encounters a construction zone where it must reduce its speed to 30 miles per hour for the next 1 hour. After passing through the construction zone, it resumes its original speed of 60 miles per hour. How far does the car travel in 4 hours? Let's think step by step and output the final answer within \boxed{}.
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