$$ \begin{aligned} \frac{2}{3}x-7 &= x&& \text{multiply ALL terms by } \color{blue}{ 3 }. \\[1 em]3 \cdot \frac{2}{3}x-3\cdot7 &= 3x&& \text{cancel out the denominators} \\[1 em]2x-21 &= 3x&& \text{move the $ \color{blue}{ 3x } $ to the left side and $ \color{blue}{ -21 }$ to the right} \\[1 em]2x-3x &= 21&& \text{simplify left side} \\[1 em]-x &= 21&& \text{switch signs on both sides} \\[1 em]x &= -21&& \\[1 em] \end{aligned} $$

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