Question

In triangle CDE, two triangles add to be 100 degrees. The third angle must be 80 degrees.

True or false?

Answer 1

Sum of angles in any triangle = 180⁰.
If sum of two angles give 100⁰, them third angle (180-100)=80⁰.
So, the answer is true.

Answer 2

true, all triangles equal 180 degrees