$$ \begin{aligned} 28-(x+9) &= 8x-8&& \text{simplify left side} \\[1 em]28-x-9 &= 8x-8&& \\[1 em]-x+19 &= 8x-8&& \text{move the $ \color{blue}{ 8x } $ to the left side and $ \color{blue}{ 19 }$ to the right} \\[1 em]-x-8x &= -8-19&& \text{simplify left and right hand side} \\[1 em]-9x &= -27&& \text{ divide both sides by $ -9 $ } \\[1 em]x &= \frac{-27}{-9}&& \\[1 em]x &= 3&& \\[1 em] \end{aligned} $$

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