Find the union $\color{blue}{A \cap B}$ of sets $A = \{ 5, 7, 3, 1\}$ and $B = \{2, 5, 9\}$.
If $A = \{a, b, c, d \}$ and $B = \{c, d, e, f\}$, find $\color{blue}{A \cup B}$.
Find difference $\color{blue}{\left( A \setminus B \right)}$ of sets $A = \{4, 5, 1, 8, 9, 6\}$ and $B = \{5, 7, 6, 8\}$.
Find Cartesian product $\color{blue}{\left( A \times B \right)}$ of sets $A = \{1, 2, 3\}$ and $B = \{x, y\}$.