angle degrees and degrees
You can find b because it is opposite the given 52 degree angle. Since on this parallelogram, there are 2 equal parallel segments that are intersected by 2 parallel lines, you know these "opposite" angles must be equal.
To find a, you just need to know that if 1 line is intersected by 2 parallel lines, the 2 angles must total to be 180 degrees.
Edit...Sorry, I did complimentary when I meant to do supplementary.
The same reasoning applies though.