What is the value of x in the diagram of Circle O below? *

Answer:
60 degrees
Step-by-step explanation:
As we know that a circle is 360 degrees, and as line AB bisects the circle, then the resulting "semi-circle" is 180 degrees. As we know that angle AC is 120 degrees, it's simple subtraction, to find that 180-120 is 60. Therefore, the value of x must be 60 degrees.
Hope this explanation helped!