$$-(20-4x-5x\cdot2) = 20-7x\cdot2$$

$$ \begin{aligned} -(20-4x-5x\cdot2) &= 20-7x\cdot2&& \text{simplify left and right hand side} \\[1 em]-(20-4x-10x) &= 20-14x&& \\[1 em]-(-14x+20) &= -14x+20&& \\[1 em]14x-20 &= -14x+20&& \text{move the $ \color{blue}{ -14x } $ to the left side and $ \color{blue}{ -20 }$ to the right} \\[1 em]14x+14x &= 20+20&& \text{simplify left and right hand side} \\[1 em]28x &= 40&& \text{ divide both sides by $ 28 $ } \\[1 em]x &= \frac{40}{28}&& \\[1 em]x &= \frac{10}{7}&& \\[1 em] \end{aligned} $$

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