In this context:
Hello! Remember you have to write complete questions in order to get good and exact answers. Here I'll assume the diagram shown below. Both ∠SV and ∠VU are central angles. This is an angle between two radii in a circle. Another fact we know is that ∠SU measures 180 degrees so it is true that:
[tex]\angle SV + \angle VU=\angle SU \ldots eq1 \\ \\ \\ But: \\ \\ \angle SV=120^{\circ} \\ \\ \angle SU=180^{\circ} \\ \\ \\ Substituting \ into \ eq1: \\ \\ 120^{\circ} + \angle VU=180^{\circ} \\ \\ \\ Isolating \ \angle VU: \\ \\ \angle VU=180^{\circ}-120^{\circ} \\ \\ \boxed{\angle VU=60^{\circ}}[/tex]