Answer:
y=29
Step-by-step explanation:
Since the angles are across a vertex from one another, they are congruent and equal. You can also see this by reflecting or folding it in half through the vertex. They will be the same. This means we can write the following equation and solve using inverse operations:
4y-8=79+y
4y-y-8=79+y-y
3y-8=79
3y-8+8=79+8
3y=87
y=29
