please help quickly!
What is the measure of Arc CB. How did you determine this?

Answer:
As shown in picture,
Angle CDF = Angle BDE = 54 deg (pair of opposite angles)
Angle CDB = 180 - CDF = 180 - 54 = 126 deg (BF is a diameter).
=> Arc CB = Angle CDB = 126 deg (property of angle on circle)
Hope this helps!
:)