$$ \begin{aligned} 0 &= \frac{c}{11}&& \text{multiply ALL terms by } \color{blue}{ 11 }. \\[1 em]11\cdot0 &= 11 \cdot \frac{c}{11}&& \text{cancel out the denominators} \\[1 em]0 &= c&& \text{ swap the left and right side of the equation } \\[1 em]c &= 0&& \text{ divide both sides by $ 1 $ } \\[1 em]c &= \frac{0}{1}&& \\[1 em]c &= 0&& \\[1 em] \end{aligned} $$

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