Hi Bre,
Since lines a and b are parallel, we know that in the image:
- ∡1 ⇔ ∡5
- ∡2 ⇔ ∡6
- ...
- ∡4 ⇔ ∡8
We're given the angle of ∡7, which is 114°. We can see that ∡7 + ∡8 will equal to 180° (since line b is a straight line) and since ∡8 ⇔ ∡4, we can deduct that ∡7 + ∡4 = 180°.
From here, it's just imputing the information and solving.
⇒ 114° + ∡4 = 180°
⇒ ∡4 = 180° - 114°
⇒ ∡4 = 66°
-Hope this helps!