In a parallelogram, opposite angles are equal and adjacent angles are supplementary, meaning they add up to 180 degrees.
Since the angle at point Y measures 30 degrees, the angle at point X, which is adjacent to Y, can be calculated as follows:
Angle at Y + Angle at X = 180 degrees
30 degrees + Angle at X = 180 degrees
Angle at X = 180 degrees - 30 degrees
Angle at X = 150 degrees
Therefore, the measure of the interior angle at point X is 150 degrees.