Explain simply why 15 is the correct answer to: John travels 150 miles in 2 hours. The speed limit is 60 mph. How many mph above the speed limit was he driving?. Explanation:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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He was driving 150 / 2 = 75 mph. So he was 75 - 60 = 15 mph above the speed limit.