Answer:
A
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
sum the 3 angles and equate to 180
5x - 6 + 89 + 57 = 180 , that is
5x + 140 = 180 ( subtract 140 from both sides )
5x = 40 ( divide both sides by 5 )
x = 8 → A
