Correct. The graphed line has slope $\displaystyle\frac{{1}}{{4}}\usepackage{cmbright}\Huge\$ since it goes through the points (0, 3) and (4, 4). Any line perpendicular to the graphed line must have slope -4 (the opposite reciprocal of $\displaystyle\frac{{1}}{{4}}\usepackage{cmbright}\Huge\$ ).