Sorry for the changing answers, did the question too fast and misinterperted the diagram. The answer below is the correct one.
Answer:
mUC=70°
Step-by-step explanation:
The angle (87) formed by two chords (US and TS) is half the sum of the intercepted arcs(104 and mUC):
87=(1/2)(104+mUC)
174=104+mUC
mUC=70°
