Thirty buyers attended an auction of dozens of cars. Ten of the buyers bought fewer than 6 cars; eight bought more than 7 cars; five bought more than 8 cars; and one bought more than 9 cars.
Of the 30 buyers, how many bought 6, 7, 8, or 9 cars?
10 people bought less than 6 and 1 bought more than 9, so the number who bought 6, 7, 8 or 9 = 30 - 10 - 1 = 19. Final Answer.
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For extra credit, we can also work out that 5 - 1 = 4 bought 9 cars.
Also, 8 - 5 = 3 bought 8 cars.
So 19 - 4 - 3 = 12 bought 6 or 7 cars.
There is no way to work out how many of those bought 6 and how many bought 7.
Just counting (spoiler)