James spends 40 years teaching. His partner has been teaching for 10 years less. How long is their combined experience? Let's answer step by step:

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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His partner has been teaching for 40 - 10 = 30 years. So together they have 40 + 30 = 70 years of experience. The answer: 70.