Rates & proportional relationships

The unit rate of change of $y$ with respect to $x$ is the amount $y$ changes for a change of one unit in $x$. The table below represents a proportional relationship with a constant unit rate of change of $y$ with respect to $x$. **Which describes a greater unit rate of change of $y$ with respect to $x$, the equation $y=4.5x$ or the table?** |||| -:|-:|-:|-: $x$|$2$|$4$|$6$| $y$|$9$|$18$|$27$|