Answer:
∠ 4 = 123°
Step-by-step explanation:
The sum of the 3 angles in the triangle = 180°
sum the 3 angles and equate to 180
9x - 6 + 6x - 1 + 82 = 180
15x + 75 = 180 ( subtract 75 from both sides )
15x = 105 ( divide both sides by 15 )
x = 7
Then
9x - 6 = 9(7) - 6 = 63 - 6 = 57
∠ 4 and 9x - 7 are adjacent angles and sum to 180°, then
∠ 4 + 57° = 180° ( subtract 57° from both sides )
∠ 4 = 123°
