Since opposite angles are the same:
angle DEC = 130
We know angle BEC + AED = 360 - 130*2
Since angles in a circle add up to 360 degrees:
BEC + AED = 360 - 260
BEC + AED = 100
This means that BEC = 50 and
AED = 50
Now that we know 2 angles in the triangle CEB we can work out y:
y = 180 - 50 - 70
y = 60 degrees
