I have answered this for 2 other people already, so I just copied my explanation here. I hope it's helpful.
Answer:
c = 21º
d = 100º
Explanation:
In questions like this, always find the angles you can find and it will help you find more and more.
So let's start by finding angle e. We know that the sum of the angles in any triangle is equal to 180. So let's do 180 - (20 + 20) = 140
angle e = 140º
Now we don't know either C or D and are unable to find them with only e, so let's find other angles to help us. The 4 angles that aren't known at each corner of the square are easy to find, as we know for sure that they fully equal to 90º. So 90 - 20 = 70º. Both angles at the bottom corners = 70º. Now for the top corners: top left = 90 - 30 = 60º and top right = 90 - 40 = 50º.
As well as this, we can find a and b as well, but I think you already figured that out. angle a: 180 - (30 + 40) = 110º, angle b: 360 - (140 + 110) = 209º
Now we can figure out c and d, because we know that the sum of all angles in any quadrilateral is 360º. So the trapezium on the left, angle c: 360 - (70 + 60 + 209) = 21º. And finally right trapezium, angle d: 360 - (70 + 140 + 50) = 100º