$$ \begin{aligned} \frac{15}{4}-7x &= 9&& \text{multiply ALL terms by } \color{blue}{ 4 }. \\[1 em]4\cdot\frac{15}{4}-4\cdot7x &= 4\cdot9&& \text{cancel out the denominators} \\[1 em]15-28x &= 36&& \text{ move 15 to the right } \\[1 em]-28x &= 36-15&& \\[1 em]-28x &= 21&& \text{ divide both sides by $ -28 $ } \\[1 em]x &= -\frac{21}{28}&& \\[1 em]x &= -\frac{3}{4}&& \\[1 em] \end{aligned} $$

This page was created using