\"\"

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The number of combinations of n distinct objects taken r at a time given by \"\".

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The given expression \"\".

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\"\"          (Apply Combination formula)

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\"\"         (Substitute n = 8 and r = 4)

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\"\"               (Subtract: \"\")\"\"

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Expand the factorial: \"\".

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\"\"

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\"\"                       (Cancel common terms)

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\"\"                             (Multiply: \"\")

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\"\"                                    (Divide: \"\")\"\"

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The value of \"\" is 70.