Respuesta :

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    3y + 12 =2(y + 30)

⇔ 3y + 12 = 2y + 60

⇔ y + 12 = 60

⇔ y = 60 - 12

⇔ y = 48

Answer:

y = 48

Step-by-step explanation:

the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.

3y + 12 is an exterior angle of the triangle , so

3y + 12 = y + 30 + y + 30 ( base angles of an isosceles Δ are congruent )

3y + 12 = 2y + 60 ( subtract 2y from both sides )

y + 12 = 60 ( subtract 12 from both sides )

y = 48

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