To solve this inequality, we first need to simplify the expression on the left side:

(х^2) + 2.5х - 18 - 1.5х + 6 > 0
х^2 + 1x - 12 > 0
(х + 4)(х - 3) > 0

Now, we need to find the critical points by setting each factor equal to zero:
х + 4 = 0
х = -4

х - 3 = 0
х = 3

Now we can create a sign chart with these critical points to determine the intervals where the inequality is true:
[ -∞, -4 ) U ( 3, ∞ ]

Therefore, the solution to the inequality is x < -4 or x > 3.