Answer:
x = 105
Explanation:
Sum of n-sided polygon = (n - 2)*180
The polygon given is a 7-sided polygon, therefore substitute n = 7 into (n - 2)*180
Sum of the polygon = (7 - 2)*180 = 900°
Thus:
x + 102 + 165 + 123 + x + 11 + 128 + 161 = 900
Add like terms
2x + 690 = 900
2x = 900 - 690
2x = 210
x = 210/2
x = 105