Answer:
[tex]\text{D) }99^{\circ}[/tex]
Step-by-step explanation:
Define a cyclic quadrilateral by a quadrilateral that is circumscribed by a circle. In this case, since the quadrilateral shown is circumscribed by a circle, it is a cyclic quadrilateral.
A property of all cyclic quadrilaterals is that their opposite angles are supplementary, meaning they add up to 180 degrees. Since [tex]\angle G[/tex] and [tex]\angle I[/tex] are opposite angles in the quadrilateral, they must be supplementary. Therefore, we have the equation:
[tex]\angle G+\angle I=180,\\81^{\circ}+\angle I=180,\\\angle I=180-81=\boxed{99^{\circ}}[/tex]
