Final answer:
The angles 21° and 25° are corresponding angles formed when a transversal intersects two parallel lines and are located on the same side of the transversal, one angle in each parallel line. Corresponding angles are always congruent.
Step-by-step explanation:
The angles 21° and 25° are corresponding angles. Corresponding angles are formed when a transversal intersects two parallel lines and are located on the same side of the transversal, one angle in each parallel line. Corresponding angles are always congruent, meaning they have the same measure.