Given:
The relation is:

To find:
The pair of coordinates that clarify why this relation is not a function.
Solution:
A relation is called a function if there exist unique y-value for each x-value. In other words, if a relation has two outputs for a single input, then the relation is not a function.
The given relation is:

This relation has two y-values 5 and 6 for a single x-value 3. Since the y-value is not unique all all values of x, therefore the relation is not a function.
Hence, the pairs of coordinates (3,5) and (3,6) clarify that the given relation is not a function.