$$ \begin{aligned} 40 &= -\frac{1}{3}(9x+30)+2&& \text{multiply ALL terms by } \color{blue}{ 3 }. \\[1 em]3\cdot40 &= -3 \cdot \frac{1}{3}(9x+30)+3\cdot2&& \text{cancel out the denominators} \\[1 em]120 &= -(9x+30)+6&& \text{simplify right side} \\[1 em]120 &= -9x-30+6&& \\[1 em]120 &= -9x-24&& \text{ swap the left and right side of the equation } \\[1 em]-9x-24 &= 120&& \text{ move -24 to the right } \\[1 em]-9x &= 120+24&& \\[1 em]-9x &= 144&& \text{ divide both sides by $ -9 $ } \\[1 em]x &= -\frac{144}{9}&& \\[1 em]x &= -16&& \\[1 em] \end{aligned} $$

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