Question 969424
The adjacent interior angles of a parallelogram are supplementary, so they add up to 180 degrees.

If one is 26 deg, the other is 180-26=154 degrees.

BUT, they want to know the difference between the two, which is not commonly asked.  The difference between the two is 154-26=128 degrees.

Here, the important part is to 
1.  Recognize that the interior angles are supplementary (add to 180 degrees).
2.  Realize the question asks for the difference between the adjacent angles, not what they are.