Respuesta :

Answer:

7) a = 60; b = 100

8) c = 20

9) d = 45

Step-by-step explanation:

7)

a + 120 = 180

a = 60

b + 80 = 180

b = 100

8)

5c + 4c = 180

9c = 180

c = 20

9)

3d + d = 180

4d = 180

d = 45

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