Respuesta :

Answer:

C. 138°

Step-by-step explanation:

< ABC = 1/2 ( ac + de)

90 = 1/2 (ac +42)

multiply each side by 2

2*90 = 2*12/ (ac+42)

180 = ac+42

subtract 42 from each side

180-42 = ac

138 = ac

For those who want a second opinion: The answer is indeed 138

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