In quadrilateral ABCD, angle BAD and angle CDA are trisected as shown. What is the degree measure of angle AFD?

Answer: AFD = 80

Explanation:

110 + 100 + 3x + 3y = 360

210 + 3x + 3y = 360

3x + 3y = 150

3(x + y) = 150

x + y = 50

Now look at polygon ABCDF (5 sided polygon)

100 + 110 + x + y + Angle F = 540

210 + 50 + angle F = 540

260 + angle F = 540

Angle F = 280

And: 

angle F + AFD = 360 degree 

280 + AFD = 360

AFD = 80