$$ \begin{aligned} 2x &= 2\cdot(-10+2x)&& \text{simplify right side} \\[1 em]2x &= -20+4x&& \\[1 em]2x &= 4x-20&& \text{move the $ \color{blue}{ 4x } $ to the left side} \\[1 em]2x-4x &= -20&& \text{simplify left side} \\[1 em]-2x &= -20&& \text{ divide both sides by $ -2 $ } \\[1 em]x &= \frac{-20}{-2}&& \\[1 em]x &= 10&& \\[1 em] \end{aligned} $$

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