It is a linear function and it satifies the table of values: $\displaystyle{y}={4}\usepackage{cmbright}\Huge\$ when $\displaystyle{x}={2}\usepackage{cmbright}\Huge\$ and $\displaystyle{y}={9}\usepackage{cmbright}\Huge\$ when $\displaystyle{x}={3}\usepackage{cmbright}\Huge\$ .