Factorial notation help please! how do i solve this problem?

Question:n(n+4)! / (n+2)! = 20 how do i solve this? what is the correct answer?

Answers:
If you solve out the !, you'll get

n(n+4)(n+3)(n+2)(n+1)(n!) / (n+2)(n+1)(n!) = 20

the (n+2)(n+1)(n!) in the numerator and the denominator cancel out so you're left with:
n(n+4)(n+3) = 20
(n)(n^2 + 7n +12) = 20
n^3 + 7n^2 + 12n - 20 = 0