[tex]30|n~~~\Longrightarrow~~~ n\vdots 30~~~\Longrightarrow~~~ \overline{1x3y}~ \vdots ~30 \\ \\
\texttt{Dar}~30 = 3 \cdot 10
\Longrightarrow~~~ \overline{1x3y} ~ \texttt{ se divide si cu 3 si cu 10.} \\ \\
\Longrightarrow~~~ \texttt{Ultima cifra este 0 pentru a fi divizibil cu 10.} \\ \\
\Longrightarrow~~~ \boxed{y = 0} \\ \\
\overline{1x30} ~\texttt{se divide cu 3} \\ \\
\Longrightarrow~~~ \boxed{x \in \{ 2; ~5; ~8\} }\\ \\
\Longrightarrow~~~ \boxed{\boxed{ A =\{1230;~1530:~1830\}}}[/tex]