The two sisters in the 400-meter circular track to practice long-distance running, for them to proce

in the same direction while running, my sister ran 390 per minute, and my sister ran 350 per minute, how many minutes after the sister to catch up with her sister?

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Sister sister more than a minute to run 40 I think we should run 400 more than her sister is 10 minutes just to catch up so bad, but I look forward to N people to answer math

400 / (390-350) = 10min