5 × ⁿP₃ = 6 × ^{n - 1}P₃ হলে n এর মান কত?

5 × ⁿP₃ = 6 × ^{n - 1}P₃
5 × n!/(n - 3)! = 6 ×(n - 1)!/(n - 1 - 3)!
5 × n!/(n - 3)! = 6 ×(n - 1)!/(n - 4)!
5 × n(n - 1)!/(n - 3)(n - 4)! = 6 ×(n - 1)!/(n - 4)!
5n/(n - 3) = 6
6n - 18 = 5n
6n - 5n = 18
n = 18