Since the roads are parallel lines, we can say that angle 4 is equal to 60 degrees, since a line is 180 degrees and 180-120=60.
We can then say that with the corresponding angles theorem, angle 4 is equal to angle 8. Since angle 7 is on the same line, and lines are 180 degrees, we can say that angle 7 is 180-60, or 120 degrees.
