Question

What does "C" represent and how do you evaluate this?

Answer 1

It represents 'combinations'.

It means that you have 9 items, and you want to count the combinations of 7 items.

The answer is:
9! / ((9-7)! * (7!))
= 9! / (2! * 7!)
= 9*8/2
= 36

Answer 2

$_9C_7=\dfrac{9!}{7!2!}=\dfrac{8\cdot9}{2}=36$