y = 7 is not a proportional function since outputs are not all the same constant multiple of their corresponding inputs. When $\displaystyle{x}={1},{y}={7}={7}\cdot{1},\usepackage{cmbright}\Huge\$ but when $\displaystyle{x}={7},{y}={7}={1}\cdot{7}.\usepackage{cmbright}\Huge\$