$$ \begin{aligned} 7x+12 &= 3x-4&& \text{move the $ \color{blue}{ 3x } $ to the left side and $ \color{blue}{ 12 }$ to the right} \\[1 em]7x-3x &= -4-12&& \text{simplify left and right hand side} \\[1 em]4x &= -16&& \text{ divide both sides by $ 4 $ } \\[1 em]x &= -\frac{16}{4}&& \\[1 em]x &= -4&& \\[1 em] \end{aligned} $$
This page was created using
Equations Solver