Since this is an isosceles triangle,
The bottom two angles are congruent.
Add the bottom two angles together, because they are both equal to 34.
34+34= 68
All the angles of a triangle are equal to 180.
180-68= 112
So, the vertex is equal to 112.
112= 4y
Divide 4 into both sides.
28= y
I hope this helps!
~cupcake