Answer:
The answer to your question is: ∠4 = 140°
Step-by-step explanation:
If there are two parallel lines cut by a transversal line 8 angles are formed.
These angles are classified as corresponding angles, alternate exterior angles, alternate interior angles and same-side angles.
Alternate exterior angles measure the same. Also alternate interior angles measure the same.
Same-side angles are supplementary angles, that means that their sum gives 180°.
Finally corresponding angles measure the same.
In the figure we notice that angles 6 and 8 are same side angles, so:
∠6 + ∠8 = 180
and ∠6 = 40° 40 + ∠8 = 180
∠8 = 180 - 40
∠8 = 140°
and ∠4 and ∠8 are corresponding angles so,
∠4 = ∠8 = 140°