Answer:
9. x = 45°
10. x = 55°
11. x = 9°
Step-by-step explanation:
[tex]9. \: x + x + 2x = 180 \\ 4x = 180 \\ x = \frac{180}{4} \\ x = 45[/tex]
[tex]10. \: x + (x - 2) + 72 = 180 \\ x + x - 2 + 72 = 180 \\ 2x + 70 = 180 \\ 2x = 180 - 70 \\ 2x = 110 \\ x = \frac{110}{2} \\ x = 55 \\ [/tex]
[tex]11. \: 4x + 3x + 13x = 180 \\ 20x = 180 \\ x = \frac{180}{20} \\ x = 9 \\ [/tex]
