Given OAC = 18^, so OCA = 18^.

here are the solutions for the remaining problems:

.1:

• Step 1: Find $y$. $OA$ and $OC$ are radii, so $\triangle OAC$ is an isosceles triangle. Given $\angle OAC = 18^\circ$, so $\angle OCA = 18^\circ$. The sum of angles in $\triangle OAC$ is $180^\circ$. $$y + 18^\circ + 18^\circ = 180^\circ$$ $$y + 36^\circ = 180^\circ$$ $$$$