Direction: Tell whether the set of ordered pairs represent a function or not.

1. (10, 20), (20, 40), (30, 60), (40, 80), (50, 100)

2. (24, 6), (20, 5), (16, 4), (8, 4), (4, 2)

3. (1, 2), (1, 3), 2, 3), (3, 3), (3, 4)

4. (0, 1), (0, 2), (1, 0), (2, 0), (0, 3)

5. (2, 5), (3, 5), (4, 5), (6, 5), (7, 5)