The venn diagram shows the number of customers who have purchased different types of pets from a pet store, where c represents customers who have purchased cats, d represents customers who have purchased dogs, and f represents customers who have purchased fish. how many people are in the set c ∩ d?

4

Step-by-step explanation:

The overlap of the blue circle C and the orange circle D contains 2 numbers. Their total is the number of customers in the intersection of the two sets:

3 + 1 = 4

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value