$$\frac{7n\cdot4-68n\cdot3+46n\cdot2-7n-18}{n-9} = 0$$

$$ \begin{aligned} \frac{7n\cdot4-68n\cdot3+46n\cdot2-7n-18}{n-9} &= 0&& \text{multiply ALL terms by } \color{blue}{ n-9 }. \\[1 em](n-9)\frac{7n\cdot4-68n\cdot3+46n\cdot2-7n-18}{n-9} &= (n-9)\cdot0&& \text{cancel out the denominators} \\[1 em]-91n-18 &= 0&& \text{ move the constants to the right } \\[1 em]-91n &= 18&& \text{ divide both sides by $ -91 $ } \\[1 em]n &= -\frac{18}{91}&& \\[1 em] \end{aligned} $$

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