Union and intersection of two sets

Statement

Let $A = \{p,q,\alpha,\beta\}$ and $B = \{q,r,\beta,\gamma\}$. Find $A \cup B$ and $A \cap B$.

Solution

The union collects all elements in $A$ or in $B$: $A \cup B = \{p,q,r,\alpha,\beta,\gamma\}.$ The intersection collects the elements in $A$ and in $B$: $A \cap B = \{q,\beta\}.$