The sum of all the angles of a triangle is 180 degrees.
If you add 90 + 90 + 90 together you get 270. These can not be the angle measures of interior angles of a triangle because the sum is more then 180.
If you add 80 + 80 + 200 together you get 360. These can not be the angle measures of interior angles of a triangle because the sum is more then 180.
If you add 40 + 50 + 60 together you get 150. These can not be the angle measures of interior angles of a triangle because the sum is less then 180.
If you add 15 +30 + 135 together you get 180! This set of angle measures can the be interior angles of a triangle!
Hope this helped!
~Just a girl in love with Shawn Mendes