Question 771267
P(n,5) = 20P(n,3) for n

n!/(n-5)!  =  20n!/(n-3)!

1/(n-5)! =  20/(n-3)!

(n-3)! = 20(n-5)!

(n-3)(n-4)= 20

n = 8

Answer: n=8

You can ask me more at: mthman@gmail.com

Thanks