There are three ways I know offhand to get x. Since the total circle is 360 degrees, x=360-238=122 degrees. Since quadrilateral BAOC has two right angles the other two angles are supplementary, x=AOC=180-58=122 degrees.
The third way is the rule they want you to recall here: Angle ABC is half the difference of the arcs:
[tex] 58^\circ = \frac 1 2 (238^\circ - x)[/tex]
Answer: Choice A, which checks when x=122 degrees.
