A) The two angles are supplementary and form a linear pair. This means that their combined measure is 180 degrees.
B) 2x + 68 = 180
C) subtract 68 from both sides. 2x = 112. Divide both sides by 2. x = 56.
If we plug 56 back into the equation 2x, we get 112. The if we add 112+68 we get 180, which means that the two are a linear pair.