first, let's only the expression with x stay on the let side: let's add 9 to both sides of the equation.
\(\frac{1}{2} x-9+9=-25+9\)
which is
\(\frac{1}{2}x=-16\)
now, let's multiply everything by 2:
\(\frac{2}{2} x=-16*2\)
\(x=-32\)
so the answer is -32!