Answer:
x = 9
Explanation:
Since you have parallel lines intersected by a transversal, the angles are congruent so set them equal to each other and solve for x.
7x + 17 = 80
Subtract 17 from both sides
7x + 17 - 17 = 80 - 17
7x = 63
Divide by 7
7x/7 = 63/7
x = 9