$$ \begin{aligned} 3 &= 3x+2(-9x+9)-9&& \text{simplify right side} \\[1 em]3 &= 3x-18x+18-9&& \\[1 em]3 &= -15x+18-9&& \\[1 em]3 &= -15x+9&& \text{ swap the left and right side of the equation } \\[1 em]-15x+9 &= 3&& \text{ move 9 to the right } \\[1 em]-15x &= 3-9&& \\[1 em]-15x &= -6&& \text{ divide both sides by $ -15 $ } \\[1 em]x &= \frac{-6}{-15}&& \\[1 em]x &= \frac{2}{5}&& \\[1 em] \end{aligned} $$

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