$$ \begin{aligned} \frac{20}{o} &= 4&& \text{multiply ALL terms by } \color{blue}{ o }. \\[1 em]o\cdot\frac{20}{o} &= o\cdot4&& \text{cancel out the denominators} \\[1 em]20 &= 4o&& \text{ swap the left and right side of the equation } \\[1 em]4o &= 20&& \text{ divide both sides by $ 4 $ } \\[1 em]o &= \frac{20}{4}&& \\[1 em]o &= 5&& \\[1 em] \end{aligned} $$

This page was created using