4. 5x + 3(2 − 3x) + 2x + 9 = 0.

\[5x+3(2-3x)+2x+9=0\]

\[5x+6-9x+2x+9=0\]

\[-2x+15=0\]

\[x=\frac{15}{2}\]

Ответ: \(x=\frac{15}{2}\).