$$ \begin{aligned} 15 &= -\frac{5}{4}y&& \text{multiply ALL terms by } \color{blue}{ 4 }. \\[1 em]4\cdot15 &= -4 \cdot \frac{5}{4}y&& \text{cancel out the denominators} \\[1 em]60 &= -5y&& \text{ swap the left and right side of the equation } \\[1 em]-5y &= 60&& \text{ divide both sides by $ -5 $ } \\[1 em]y &= -\frac{60}{5}&& \\[1 em]y &= -12&& \\[1 em] \end{aligned} $$

This page was created using