If angle ec is a bisector then angles Bec and ced are the same making them both 4x+1. we know a line segment equals 180°. so if we take the 11x-12 and add it to 2(4x+1) we end up with 19x-10=180. you add 10 to both sides and get 19x=190 then you divide by both sides. you'll end up with x=10. you plug In the 10 with aeb and aec and add them together to get 139°. if you're looking for the equation, it's 15x-11.
