C(9,6)
\(\begin{array}{|rcll|} \hline && C(9,6) \\ &=& C(9,9-6) \\ &=& C(9,3) \\ &=& \frac{9}{3}\cdot \frac{8}{2}\cdot \frac{7}{1} \\ &=& 3\cdot 4\cdot 7 \\ &=& 84 \\ \hline \end{array}\)
