Answer:
∠ FAB = 75°
Explanation:
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ FAB is an external angle, thus
13x - 3 = 3x + 2 + 55 = 3x + 57 ( subtract 3x from both sides )
10x - 3 = 57 ( add 3 to both sides )
10x = 60 ( divide both sides by 10 )
x = 6
Thus
∠ FAB = 13x - 3 = 13(6) - 3 = 78 - 3 = 75°