1. **State the problem:** We have two angle pairs formed by two parallel lines cut by a transversal. The first pair has angles 80° and 69° with an unknown angle $x$. The second pair has angles 72° and $x$. We need to classify the marked angle pairs and find the value of $x$. 2. **Classify the angle pairs:** - For the first pair (80°, 69°, and $x$), since $x$ is inside the parallel lines and on opposite sides of the transversal, these are **alternate interior angles**. - For the second pair (72° and $x$), since both are outside the parallel lines and on opposite sides of the transversal, these are **alternate exterior angles**. 3. **Use the property of alternate interior and alternate exterior angles:** Alternate interior angles are equal, and alternate exterior angles are equal when lines are parallel. 4. **Set up equations:** - For the first pair: $x = 69°$ - For the second pair: $x = 72°$ 5. **Check for consistency:** Since $x$ cannot be both 69° and 72°, we must consider the diagram carefully. The first $x$ is inside the angle pair near the transversal (alternate interior), so $x = 69°$. 6. **Final answer:** $$x = 69°$$