Answer:
111°
Step-by-step explanation:
The polygon given is a heptagon having 7 sides.
Sum of interior angles of a 7-sided polygon = (n - 2)*180
= (7 - 2)*180
= 5*180 = 900°
Therefore:
126° + 158° + 120° + 125° + 121° + 139° + x° = 900°
Solve for x
789° + x° = 900°
Subtract 789 from each side
x = 900° - 789°
x = 111°
