2. a. x + y = 90 degrees due to the sum of angle/total of a triangle which is 180 degrees. As shown on the picture, the third angle is represented as an right angle which makes it obvious that it’s 90 degrees. Basic math shows that 90 degrees + 90 degrees = 180 degrees. Simple as that. b. 90 – 37 = 53 degrees 3. (6-2) x 180 degrees. = 4 x 180 degrees. 720 degrees. 4.