I need help with this.

Answer:
[tex]x + (3x - 9) = 5x - 30 \\ x + 3x - 9 = 5x - 30 \\ 4x - 9 = 5 x - 30 \\ - 9 + 30 = 5x - 4x \\ 21 = x \\ so..value \: of \: x \: is \: 21 \\ so. \\ <ACD = 5 \times 21 - 30 = 105 - 30 = 75° \\ < ACB = 180° - 75° = 115°[/tex]
<ACB = 105°
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