$$ \begin{aligned} 6(b-2) &= 5\cdot(9+b)&& \text{simplify left and right hand side} \\[1 em]6b-12 &= 45+5b&& \\[1 em]6b-12 &= 5b+45&& \text{move the $ \color{blue}{ 5b } $ to the left side and $ \color{blue}{ -12 }$ to the right} \\[1 em]6b-5b &= 45+12&& \text{simplify left and right hand side} \\[1 em]b &= 57&& \\[1 em]b &= 57&& \\[1 em] \end{aligned} $$

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