Answer:
x = 111
Step-by-step explanation:
The sum of the interior angles of a polygon is
sum = 180° (n - 2) ← n is the number of sides
Here n = 7, thus
sum = 180° × 5 = 900°
Sum the given interior angles and equate to 900
x + 139 + 121 + 125 + 126 + 158 + 120 = 900, that is
x + 789 = 900 ( subtract 789 from both sides )
x = 111
