Answer:
x = 105
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 interior angles and equate to 900
x + 102 + 165 + 123 + x + 11 + 128 + 161 = 900, that is
2x + 690 = 900 ( subtract 690 from both sides )
2x = 210 ( divide both sides by 2 )
x = 105
