Answer:
The variable is 8/7.
Explanation:
Givens
![\angle C = -x+8\\arcAB=12x](https://img.qammunity.org/2019/formulas/mathematics/high-school/eywqnimgv1rl5qkm7ld6id56ji44lmb5oh.png)
To solve this problem, we need to use the Inscribed Angle Theorem which states that an angle inscribed in a circle is half of the subtended arc.
Based on this theorem, we have
![\angle C=(1)/(2)arcAB](https://img.qammunity.org/2019/formulas/mathematics/high-school/8n0zakfzq2x7lwf2khpas4f75ve2h9id2v.png)
Replacing each expression
![-x+8=(1)/(2)(12x)\\ -x=6x-8\\8=x+6x\\7x=8\\x=(8)/(7)](https://img.qammunity.org/2019/formulas/mathematics/high-school/ixfu44jqro6gqbmhlgs6rtzvjcc9r07t8z.png)
Therefore, the variable is 8/7.