What is the value of the expression 12c5

Question

Trying to solve this problem too

Answer 1

_nC_r = n!/[(r!)(n-r)!] = "n choose r"

 

So, ₁₂C₅ = 12!/[(5)!(7!]

 

                = (12)(11)(10)...(3)(2)(1)

                   ---------------------------------     = 792

                    (5)(4)(3)(2)(1)(7)(6)(5)....1