Answer:
x = 15
Step-by-step explanation:
FD and AC are parallel because both are perpendicular to EB. Angle EDF and Angle DCA are congruent because they are corresponding angles. The measure of Angle DCA is also 3x because congruent angles have the same measure.
Now consider Triangle ACD. Because the sum of all three measures of the angles in a triangle add up to 180°.
x + 8x + 3x = 180°
12x = 180°
12x/12 = 180/12
x = 15
