Correct. Because $\displaystyle\angle{V}{S}{T}\usepackage{cmbright}\Huge\$ is a right angle, it measures $\displaystyle{{90}}^{\circ}\usepackage{cmbright}\Huge\$ . Because $\displaystyle\angle{R}{S}{T}\usepackage{cmbright}\Huge\$ is a straight angle, $\displaystyle\angle{R}{S}{V}\usepackage{cmbright}\Huge\$ also measures $\displaystyle{{90}}^{\circ}\usepackage{cmbright}\Huge\$ . Therefore, the measure of $\displaystyle\angle{U}{S}{V}\usepackage{cmbright}\Huge\$ is $\displaystyle{90}-{51}={39}\usepackage{cmbright}\Huge\$ degrees.