Answer:
angle number 1
Step-by-step explanation:
An angle that is vertical to <UXR is an angle that is directly opposite to <UXR, which share the same vertex, X, as <UXR.
From the diagram given, the angle number that shares the same vertex as <UXR and is directly opposite to <UXR is angle number 1 (<SXT).
<1 = <UXR
