This problem needs more information. Probably a picture of a figure with several angles from which you can state the relationship between the angle 4 and the angle 8.
Then I have to assume this relation to show you how to work.
My assumptio will be that angle 4 and angle 8 are vertically opposite triangles.
That means that both triangles are congruent.
Then 3x = x + 40
=> 2x = 40
=> x = 20
Then agle 4 is 3x = 3*20 = 60 degrees.
Answer: 60 degrees, subject to the assumption considered.