Answer:the measure of angle 6 is 60 degrees.
Explanation:
The two horizontal lines ate straight and parallel lines. It is established that the sum of the angles on a straight line is 180 degrees. Looking at the given figure, angle 5 and angle 6 are on a straight line. Therefore
Angle 5 + angle 6 = 180 degrees. Therefore,If angle 5 is 120 degrees,then
Angle 6 + 120 = 180
Angle 6 = 180 - 120 = 60 degrees.