First, let's simplify the expression on the left side:

(x-3)(x+2) - (x-3)^2 = x^2 + 2x - 3x - 6 - (x^2 - 6x + 9)
= x^2 - x - 6 - x^2 + 6x - 9
= 5x - 15
= 5(x - 3)

So now we have:
5(x - 3) > 15x + 10

Expanding:
5x - 15 > 15x + 10

Rearranging:
5x - 15 - 15x > 10
-10x - 15 > 10
-10x > 25
x < -2.5

Therefore, the solution to the inequality is x < -2.5.