The value of x is 11.
Central Angle Theorem :
It states that the central angle from two chosen points A and B on the circle is always twice the inscribed angle from those two points.
From given figure, [tex]A=3x+9,B=8x-4[/tex]
[tex]\angle B=2\angle A\\\\8x-4=2(3x+9)\\\\8x-4=6x+18\\\\8x-6x=18+4\\\\2x=22\\\\x=22/2=11[/tex]
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