Pls help, with explanation :) I will give brainliest

Answer:
C,110°
Step-by-step explanation:
when the angle on circumference=50°
then the angle at center=2×50=100°
other angles of this triangle are equal and each=1/2(180-100)=1/2×80=40
so angle of quadrilateral=30+40=70°
as opposite angles of a cyclic quadrilateral are supplementary.
so y+70=180
y=180-70=110°