Because of the parallel lines, the angle above z is 71° because it's corresponding angles.
Adjacent angles on a straight line add up to 180°
z + 71 = 180
z = 109°
Because of the parallel lines, (5y - 6) = z because it's vertically opposite angles.
Substitute z = 109
5y - 6 = 109
5y = 115
y = 23°