$$ \begin{aligned} \frac{81}{5}+2y &= 78&& \text{multiply ALL terms by } \color{blue}{ 5 }. \\[1 em]5\cdot\frac{81}{5}+5\cdot2y &= 5\cdot78&& \text{cancel out the denominators} \\[1 em]81+10y &= 390&& \text{ move 81 to the right } \\[1 em]10y &= 390-81&& \\[1 em]10y &= 309&& \text{ divide both sides by $ 10 $ } \\[1 em]y &= \frac{309}{10}&& \\[1 em] \end{aligned} $$

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