$$ \begin{aligned} 12 &= 4(x-4)-8x&& \text{simplify right side} \\[1 em]12 &= 4x-16-8x&& \\[1 em]12 &= -4x-16&& \text{ swap the left and right side of the equation } \\[1 em]-4x-16 &= 12&& \text{ move -16 to the right } \\[1 em]-4x &= 12+16&& \\[1 em]-4x &= 28&& \text{ divide both sides by $ -4 $ } \\[1 em]x &= -\frac{28}{4}&& \\[1 em]x &= -7&& \\[1 em] \end{aligned} $$

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