Answer:
x = 12
Step-by-step explanation:
The mistake made here is in making 130 = 9x + 7. They are not the same.
The central angle = 130 degrees.
Any angle sharing the endpoints of the central angle and having it's vertex on the same side of the central angle is 1/2 the central angle.
1/2 the central angle = 130 /2 = 65
Cyclic quadrilaterals (those with all 4 points touching a circle's circumference) have opposite angles supplementary.
65 + 9x + 7 = 180 Combine like terms on the left
72 + 9x = 180 Subtract 72 from both sides
72 - 72 + 9x = 180-72 Combine
9x = 108 Divide by 9
9x/9 = 108/9
x = 12
