If you are given the measure of angle 4, then we know angle 2 is equal since it is a vertical angle. The angle of a line is 180 degrees, so subtract the measure of angle 4 (and/or 2) which will give you the angle measure for both angle 1 and 3, since those are also equal due to vertical angles. Hope that helped! :)
Conclusion: 8th Graders like pop music more because 72 out of the 90 in 8th grade Dave surveyed enjoy it, compared to the 60 out of 80 in 7th grade that enjoyed it.