You may have thought that a line perpendicular to $\displaystyle{y}=\frac{{3}}{{4}}{x}-{2}\usepackage{cmbright}\Huge\$ , which has a slope of $\displaystyle\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ , has a slope that is the reciprocal of $\displaystyle\frac{{3}}{{4}}\usepackage{cmbright}\Huge\$ . However, the slopes of perpendicular lines are negative reciprocals of each other.