Simplify completely x^2-10x-24/x^2-3x-108 and find the restrictions on the variable

Simplify the expression:
x + 2/x + 9
Hope this helps!
I don't know if this is correct, but I'm trying

Steps
x^2 - 10x -24/x^2 - 3x - 108
First, factor x^2 - 10x -24: (x + 2)(x - 12)
= (x + 2)(x - 12)/x^2 - 3x - 108
Second, factor x^2 - 3x - 108: (x + 9)(x - 12)
= (x + 2)(x - 12)/(x + 9)(x - 12)
Third, cancel the common factor: x - 12
= x + 2/x + 9

He will need 2,898 pieces of paper