Answer:
Alternate interior angles are congruent; same-side interior angles are supplementary.
Explanation:
When two parallel lines are cut by a transversal, the interior angles will be the angles between the two parallel lines. Alternate interior angles will be on opposite sides of the transversal; the measures of these angles are the same.
Same-side interior angles will be on the same side of the transversal; the measures of these angles will be supplementary, adding up to 180 degrees.