left triangle has a 90 degree angle so 90 plus 35 equals 125. 180 is the total angles in a triangle so subtract to get A. A = 55. The angle of A also helps for B. 55 is part of 180 (a strait line) so that means B is 125. A and C are the same because the is is 2 strait lines intersecting. C is 55. Now for the right triangle. 55 + 70 is 125. do the same thing as we did for A and you should get 55 for D.
Hope this helps!