Assuming these lines are perpendicular
Opposite angles are congruent therefore
77 = 6x + 23
6x = 54
X = 9
And supplementary angles sum up to be 180 degrees where in this case we can take angle 77 degrees and z which makes
77 + z = 180
Z = 103 degrees
Therefore,
x = 9 degrees
z = 103 degrees