Answer:
140°
Step-by-step explanation:
The external angle is half the difference between the intercepted arcs. One arc is shown as 30°. The other will be the difference between 180° and (30°+x). Then we have ...
(30 -(180 -(30+x)))/2 = 10
x -120 = 20 . . . . . . . multiply by 2 and simplify
x = 140 . . . . . . . . . . . add 120
The measure of arc X is 140°.
