$\frac{\binom{9}{2}\binom{6}{1}}{\binom{15}{3}}$

$\frac{\binom{9}{1}\binom{6}{2}}{\binom{15}{3}}$

$\frac{9}{15} \times \frac{8}{14} \times \frac{6}{13}$

$\binom{9}{2} + \binom{6}{1}$