Resposta:

São ângulos suplementares, a soma deles é igual a 180⁰.

1) 2x + 5 + 65 = 180

2x = 180 - 5 - 65

2x = 110

x = 110/2

x = 55⁰

2) 5x + 25 + 45 = 180

5x = 180 - 25 - 45

5x = 180 - 70

5x = 110

x = 110/5

x = 22⁰

3) 3x - 17 + 122 = 180

3x = 180 + 17 - 122

3x = 75

x = 75/3

x = 25

4) 4x - 30 + 100 = 180

4x = 180 + 30 - 100

4x = 110

x = 110/4

x = 27,5⁰

5) 4x + 12 + 136 = 180

4x = 180 - 12 - 136

4x = 32

x = 32/4

x = 8⁰

6) 7x - 8 + 76 = 180

7x = 180 + 8 - 76

7x = 112

x = 112/7

x = 16⁰

7) 8x - 36 + 80 = 180

8x = 180 + 36 - 80

8x = 136

x = 136/8

x = 17⁰

8) x + 40 + 52 = 180

x = 180 - 40 - 52

x = 88⁰