How do i find the measurement for the angle with the question mark

It is 20 degrees because it is the same angle as the one below and to the left of it. It is called congruent angles.
Hope this helped!

So we know that a triangle equals 180 degrees. You can subtract 20 from 35 and get 15. !5 would be the missing value for the first triangle. Also since you have a vertical angle, missing angle would be 15 as well. Now you can do 180-156 because it is linear. You would get 24. And now for this step, I think you subtract 24-15 to get the missing value which is 9.