Answer: Choice A
The notation P(15,10) refers to the equation
P(n,r) = (n!)/(n-r)!
where n = 15 and r = 10. So,
P(15,10) = (15!)/(15-10)!
P(15,10) = (15!)/(5!)
which is close to the original expression but it is missing the 10! part in the denominator. Instead you'll use a combination formula
