I'm not sure, but I think x is 30 degrees and y is 40 degrees.
(If you want an explanation, then you can ask. The reason why I didn't give one, is I'm not too sure.)
There might be a better way to determine those angles – there probably is a better way to determine those angles – but here's what I thought of.
Move to the left of the angle marked 3y and draw a perpendicular between lines e and f.
This creates a five sided figure. The sum of the interior angles of a polygon of n sides is (n – 2) • 180o
The sum of the interior angles of the pentagon is 540o
Note that one of the interior angles is the supplementary angle of 2x so its value is (180o – 2x)
The five angles:
90o - one of the angles newly created with the perpendicular line
90o - the other angle newly created with the perpendicular line
3y - another angle
(180o – 2x) - another angle
a - the angle we want to find
a = 540o minus all the other angles
a = 540o – 90o – 90o – 3y – (180o – 2x)
a = 540o – 180o – 3y – 180o + 2x
a = 2x – 3y + 180o