Answer
$36$
Work Step by Step
We know that $ n!=1 \cdot 2 \cdot 3 .....(n-1)n $
Thus, we have $\dfrac{9!}{(9-2)!2!}$
$= \dfrac{9\cdot 8 \cdot 7 \cdot 6 \cdot 5 \cdot 4 \cdot 3 \cdot 2 \cdot 1}{5 \cdot 4 \cdot 3 \cdot 2 \cdot 1 \times 2 \cdot 1 }$
$=36$
