Adjacent angles of a straight line will always add up to 180
So we can do 180-130=50
So the measure of the angle at the top is 50
We also know that the angles of a triangle always add up to 180, so because we now have all of the measure angles we can solve for y using an equation
The equation is:
y+y+50=180
We'll want to isolate y, so first we should combine like terms, the equation is now
2y+50=180
Next subtract 50 from both sides, the equation is now
2y=130
We'll then divide each side by 2, so we can y by itself
So 2y/2=y
130/2=65
So y=65
We can check this by adding up the inside of the angles of the triangle, they should add up to 180
65+65=130
130+50=180
So this confirms our answer of y=65
