$$ \begin{aligned} u+\frac{27}{3} &= 0&& \text{multiply ALL terms by } \color{blue}{ 3 }. \\[1 em]3u+3\cdot\frac{27}{3} &= 3\cdot0&& \text{cancel out the denominators} \\[1 em]3u+27 &= 0&& \text{ move the constants to the right } \\[1 em]3u &= -27&& \text{ divide both sides by $ 3 $ } \\[1 em]u &= -\frac{27}{3}&& \\[1 em]u &= -9&& \\[1 em] \end{aligned} $$

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