$$ \begin{aligned} 100+100+\frac{9}{10}y &= y&& \text{multiply ALL terms by } \color{blue}{ 10 }. \\[1 em]10\cdot100+10\cdot100+10 \cdot \frac{9}{10}y &= 10y&& \text{cancel out the denominators} \\[1 em]1000+1000+9y &= 10y&& \text{simplify left side} \\[1 em]9y+2000 &= 10y&& \text{move the $ \color{blue}{ 10y } $ to the left side and $ \color{blue}{ 2000 }$ to the right} \\[1 em]9y-10y &= -2000&& \text{simplify left side} \\[1 em]-y &= -2000&& \text{switch signs on both sides} \\[1 em]y &= 2000&& \\[1 em] \end{aligned} $$

This page was created using