$$ \begin{aligned} -2r-5(-5r+9) &= 6r+9+7&& \text{simplify left and right hand side} \\[1 em]-2r-(-25r+45) &= 6r+16&& \\[1 em]-2r+25r-45 &= 6r+16&& \\[1 em]23r-45 &= 6r+16&& \text{move the $ \color{blue}{ 6r } $ to the left side and $ \color{blue}{ -45 }$ to the right} \\[1 em]23r-6r &= 16+45&& \text{simplify left and right hand side} \\[1 em]17r &= 61&& \text{ divide both sides by $ 17 $ } \\[1 em]r &= \frac{61}{17}&& \\[1 em] \end{aligned} $$

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