Respuesta :

Answer:50

Step-by-step explanation:

a right angle is always 90 degrees and we know triangles add to 180 degrees. So add 90 and 40 to get 130. Then subtract 180 from 130 to get 50.

50 because there can only be 1- 90 degrees angle in a triangle. A 180 angle is a strait line. You can go through a process of elimination