Answer:
x=27
Explanation:
We know that the sum of the internal angles of a polygon is the number of sides less two times 180.
There are 7 sides to the figure, so (7-2)*180 = 900
120 + 129 + 138 + 135 + (2x+73) + 128 + 123 = 900
2x + 846 = 900
2x = 54
x=27