Answer:
∠ A = 67°
Explanation:
the sum of the 3 angles in a triangle = 180°
sum the 3 angles, equate to 180 and solve for x
8x - 6 + 6x + 7 + 39 = 180 ( collect like terms on left side )
14x + 40 = 180 ( subtract 40 from both sides )
14x = 140 ( divide both sides by 14 )
x = 10
Then
∠ A = 6x + 7 = 6(10) + 7 = 60 + 7 = 67°