Answer:
30
Step-by-step explanation:
There are multiple ways to solve the problem but the easiest and fastest way is to know that when two lines intersect, the opposite angles are always same.
another way to approach this is, 1+2=180 as it is a line. and 3+4=180. but 2+3=180 as well as 3+4=180.
from this relation you can easily say that angle 2 would be 180-30, which gives us 150. But since 2+2=180, angle 3 would be 180-150, which would give us 30. (it is a longer way to do it, but it shows you why opposite angles in two lines are always same)
