Answer:
m∠C = 72°
Step-by-step explanation:
The sum of the angles in the triangle is 180°.
A +B +C = 180°
(2x +11)° +(3x -8)° +(4x -12)° = 180°
9x = 189 . . . . . . . . divide by °, add 9
x = 21 . . . . . . . . . divide by 9
Angle C is ...
(4x -12)° = (4(21) -12)° = 72° . . . . angle C
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Additional comment
Angle A is 53°; angle B is 55°.
