C (18, r) = C (18, r + 2). Then C(r, 5) ...

C (18, r) = C (18, r + 2). Then C(r, 5) =

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The number of ways in which a 7 people can sit around a round table is
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The number of ways in which 7 people can sit around a table if two per...
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C (18, r) = C (18, r + 2). Then C(r, 5) =
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