$$ \begin{aligned} 9x-4 &= 3x+3&& \text{move the $ \color{blue}{ 3x } $ to the left side and $ \color{blue}{ -4 }$ to the right} \\[1 em]9x-3x &= 3+4&& \text{simplify left and right hand side} \\[1 em]6x &= 7&& \text{ divide both sides by $ 6 $ } \\[1 em]x &= \frac{7}{6}&& \\[1 em] \end{aligned} $$