You can see that the two lateral and vertical sides of the quadrilateral are congruent respectively, meaning that ∠3x = ∠(2x+33).
You also know that 3x + y = 180° since they're supplementary.
To solve for x, just solve the equation I wrote above:
3x = (2x+33) (subtract 2x from both sides, and that automatically gives you
x = 33 the value)
To solve for y, plug it into the second equation I provided:
3(33) + y = 180
99 + y = 180
y = 81
∴ x = 33, y = 81
