∠BEC ≅ ∠CED definition of angle bisector
∠BEC = ∠CED definition of congruency
∠AEB , ∠BEC, and ∠CED are supplementary
∠AEB + ∠BEC + ∠CED = 180 definition of supplementary angles
∠AEB + ∠CED + ∠CED = 180 substitution
11x - 12 + 4x + 1 + 4x + 1 = 180 substitution
19x - 10 = 180 simplified (added like terms)
19x = 190 addition property of equality
x = 10 division property of equality
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∠AEB = 11x - 12
= 11(10) - 12
= 110 - 12
= 98
∠BEC = ∠CED = 4x + 1
= 4(10) + 1
= 40 + 1
= 41
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∠AEB + ∠BEC = ∠AEC segment addition property
98 + 41 = ∠AEC substitution
139 = ∠AEC simplified (added like terms)
Answer: 139°