Vertical angles are equal, so
.. 3x +8 = 5x -20
.. 28 = 2x . . . . . . . . add 20-3x
.. 14 = x . . . . . . . . . . divide by 2
Each of the vertical angles is 3*14 +8 = 50°, so the supplementary one is 130°.
.. 5*14 +4y = 130
.. 4y = 60 . . . . . . . . subtract 70
.. y = 15 . . . . . . . . . . divide by 4
The values of interest are
.. x = 14
.. y = 15