Sarah and her friend Emily are participating in a charity walkathon. Sarah walks at an average speed of 3 miles per hour, while Emily walks at an average speed of 4 miles per hour. They start walking from the same point and at the same time. If Emily arrives at the finish line 1 hour earlier than Sarah, how long did it take Sarah to complete the walkathon? Also, what is the distance of the walkathon? Let's think step by step and output the final answer within \boxed{}.
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