$$ \begin{aligned} 7+4 \cdot \frac{x}{3} &= 19&& \text{multiply ALL terms by } \color{blue}{ 3 }. \\[1 em]3\cdot7+3\cdot4 \cdot \frac{x}{3} &= 3\cdot19&& \text{cancel out the denominators} \\[1 em]21+4x &= 57&& \text{ move 21 to the right } \\[1 em]4x &= 57-21&& \\[1 em]4x &= 36&& \text{ divide both sides by $ 4 $ } \\[1 em]x &= \frac{36}{4}&& \\[1 em]x &= 9&& \\[1 em] \end{aligned} $$

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