Answer: 9
Step-by-step explanation:
The angles marked are corresponding angles, since they correspond in the same direction. Both are pointing to the southwest direction.
Since line DE is parallel to line FG, this means the corresponding angles mentioned are congruent.
Set them equal to each other and solve for x.
7x+18 = 81
7x = 81-18
7x = 63
x = 63/7
x = 9