To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $4$ and $3$ is $12$. Multiply $\frac{1-3x}{4}$ times $\frac{3}{3}$. Multiply $\frac{2x+1}{3}$ times $\frac{4}{4}$.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $4$ and $3$ is $12$. Multiply $\frac{1-3x}{4}$ times $\frac{3}{3}$. Multiply $\frac{2x+1}{3}$ times $\frac{4}{4}$.
