$$ \begin{aligned} 30-10+\frac{10}{2}x\cdot2 &= 0&& \text{multiply ALL terms by } \color{blue}{ 2 }. \\[1 em]2\cdot30-2\cdot10+2 \cdot \frac{10}{2}x\cdot2 &= 2\cdot0&& \text{cancel out the denominators} \\[1 em]60-20+20x &= 0&& \text{simplify left side} \\[1 em]20x+40 &= 0&& \text{ move the constants to the right } \\[1 em]20x &= -40&& \text{ divide both sides by $ 20 $ } \\[1 em]x &= -\frac{40}{20}&& \\[1 em]x &= -2&& \\[1 em] \end{aligned} $$

This page was created using