Question

What angles are supplementary angles?

Answer 1

Supplementary angles, as you may recall, are two angles whose sum is 180°. 

However, as you may also recall, 180° has the angle measure forming a line(or line segment, I don't remember).

But the two angles must be CONNECTED! And must form A LINE!

Thus: 

The answer is IHF and GHF.

P.S. IXL, huh?