To find a know that 180 degrees is a straight line, and subtract 70 from 180 to get 110 degrees. To find b, know that the angles between parallel lines add up to 180, and if you know a is 110 you know b is 70. Then, find out c by knowing that all three angles of a triangle add up to 180, and you have 60 given and you found out b is 70, so you know c is 60 plus 70 which is 130 and 180-130 is 50 degrees. Lastly, to find d you need use the same strategy you used to find b( know that the angles between parallel lines add up to 180) and you get 130 degrees.
