Line b is a straight line which is 180 degrees.
Angle 5 plus angle 6 need to equal 180
Angle 5 = 180 - 128 = 52
Angle 1 is the same as angle 5 because they are located in the same place on a straight line.
Angle 1 = 52 degrees.
Angle 3 is a vertical angle to angle 1, which means they are identical so angle 3 is also 52 degrees.
