Solve for x.

(5x^2 - 12x) / (x^2 + 5x - 24) <= 0

You should multiply both sides by x^2+5x-24 so we get

5x^2-12x <= 0
now we get
5x^2 <= 12x
Divide both sides by x and we get
5x <=12 so
x <= 12/5