A one-unit increase in $X$ is associated with a $\beta_1$ percent increase in $Y$.

A one-unit increase in $X$ is associated with a $100 \cdot \beta_1$ percent change in $Y$.

The elasticity of $Y$ with respect to $X$ is $\beta_1$.

A one-unit increase in $X$ increases $Y$ by $\beta_1$ units.