This is actually quite simple. You just have to remember that a triangles angle measures must equal up to 180. Also, you need to recognize which angles are supplementary angles (angles whose measure must add up to 180) That being said, 126 and A are supplementary angles. So are C and 41, and E and 38. To find out A, simply subtract 126 from 180 to get 54. Then, to get C, subtract 41 from 180 to get 139. Since you know A and C, you can figure out B, which is 85. Then, to find E, subtract 138 from 180. That equals 42. Now, simply add up 41 and 42, and shbtract it from 180. That gives you 97, which is D. I hope this helps! :)
