Задача 3.

For each two of the following sets show if one is a subset of the other: \begin{equation*} \{1\}, \{1,2\}, \{1,2,3\},  \{\{1\},2,3\}, \{\{1,2\},3\},  \{3,2,1\}, \{\{2,1\}\}. \end{equation*}