Answer: \(x\lt -4\) or \(x\gt 4\).

Expand the left side:

\((x+5)(x-2)=x^2+3x-10.\)

So

\(x^2+3x-10\gt 3x+6.\)

Subtracting \(3x+6\) from both sides gives

\(x^2-16\gt 0.\)

Factorise:

\((x-4)(x+4)\gt 0.\)

The product is positive outside the two roots, so

\(x\lt -4\quad\text{or}\quad x\gt 4.\)