Answer:
B
Explanation:
AB = AC
means it is an isoceles triangle (both legs are equal).
that then had a a consequence that both angles at the baseline are equal. in our case the angles B and C.
because p is parallel to BC, the small triangle of A with the line p is a similar triangle to the larger ABC.
that means all angles in one triangle are the same as the angles in the other triangle (and all sides have the same scaling factor, but that is not needed here).
now we need to remember 2 general rules :
1. the sum of all angles in a triangle is always 180°.
2. the sum of all angles around a single point on one side of a line is also 180°.
because of 1. for an isoceles triangle (B = C) we get
180 = 36 + 2×C
144 = 2×C
C = 72°
because of the similar triangles, C is also equal to the inner angle of y.
and because of 2. we get
180 = 72 + y
y = 108°