Question

x^2+4x-24/x-3

Answer 1

I will assume that you mean

(x^2+4x-24)/(x-3)
Where you put parentheses makes all the difference.

x-3 is not a factor of (x^2+4x-24), so it is not possible to simplify the expression.

It is not clear just what the question is. All you have done is write a formula.