In this work I found out that in order to find X in the triangle I had to add up two angles, and subtract the answer to 180 and I get the answer for X.
When you match up all the vertices you create a line.
The triangle sum postulate: the angles of a triangle add to 180°
Exterior angles are supplementary
180°-115°=65°
43°+82°+x=180° triangle sum postulate
Triangle: 180/3=60° equiangular
Only ONE angle can be right or obtuse