If a relation is a function, how many y-values can each x-value have?
Yes.
Practice makes perfect
For a relation to be a function, each x-value can only be paired with one y-value, but one y-value can be paired with multiple x-values.
(1,1), (2,0), (3,1), (4,3), (0,2)
Examining the ordered pairs, we can see that there is no x-value with multiple y-values. Therefore, the relation is a function.