[tex]\it X\cap Y =\{a,\ c,\ e\} \Rightarrow \begin{cases} \it \{a,\ c,\ e\}\subset\ X\\ \\ \it \{a,\ c,\ e\}\subset\ Y \end{cases}\ \ \ \ \ (1)\\ \\ \\ X\setminus Y=\{b,\ d,\ u\} \Rightarrow \begin{cases} \it \{b,\ d,\ u\}\subset\ X\\ \\ \it \{b,\ d,\ u\} \not\subset\ Y \end{cases}\ \ \ \ \ (2)\\ \\ \\ X\cup Y=\{a,\ b,\ c,\ d,\ e,\ f,\ g,\ u\}\Rightarrow \begin{cases} \it X \subset\{a,\ b,\ c\,\ d,\ e,\ f,\ g, u\}\\ \\ \it Y \subset\{a,\ b,\ c\,\ d,\ e,\ f,\ g, u\} \end{cases}\ \ \ \ (3)[/tex]
[tex]\it (1),\ (2),\ (3) \Rightarrow X=\{a,\ b,\ c,\ d,\ e,\ u\},\ \ Y=\{a,\ c,\ e,\ f,\ g\}[/tex]
