Explanation:
line n (and if it is parallel or not) has nothing to do with this solution. it is only there to confuse us.
the sum of all angles around a single point on one side of a line is 180° (because the line can act as the diameter of a circle with the point being is center, and a half-circle stands for 180°).
so,
180 = (6x - 19) + (8x + 3)
180 = 6x - 19 + 8x + 3 = 14x - 16
90 = 7x - 8
98 = 7x
x = 98/7 = 14