A runs at 6 m/s and B at 5 m/s. In a race, A beats B by 15 seconds. What is the length of the race?
Correct answer C. 450 m
Explanation
L/5 − L/6 = 15 gives L/30 = 15, so the race is 450 m. Check: B takes 90 s and A takes 75 s.
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