A runner jogs along a straight path, covering a certain distance each day. On the first day, she jogs 3 miles. Each subsequent day, she jogs 2 miles more than the previous day. She continues this pattern for 6 days. On the seventh day, she returns to her starting point by jogging in the opposite direction, covering the same total distance she jogged over the first 6 days. What is the total distance she jogs on the seventh day? Let's think step by step and output the final answer within \boxed{}.
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