$\frac{ 9 ! }{ 3 ! \times \left( 9-3 \right) ! }$
Use $n !=n \times \left( n-1 \right) !$ to expand the expression$\frac{ 9 \times 8 \times 7 \times 6 ! }{ 3 ! \times \left( 9-3 \right) ! }$
Subtract the numbers$\frac{ 9 \times 8 \times 7 \times 6 ! }{ 3 ! \times 6 ! }$
Cancel out the common factor $6 !$$\frac{ 9 \times 8 \times 7 }{ 3 ! }$
Calculate the product$\frac{ 504 }{ 3 ! }$
Calculate the factorial$\frac{ 504 }{ 6 }$
Cancel out the common factor $6$$84$