[tex]A = \Big\{x = \overline{7a2b}~\Big| ~x~\vdots~45 \Big\}\\\\
45=9\times 5\\
\text {Un numar este divizibil cu 45 daca este divizibil cu 5 si cu 9}\\\\
\overline{7a2b}~\vdots~5 ~~\Longrightarrow~~ b \in \{0; ~5\}\\\\
\overline{7a2b}~\vdots~9 ~~\Longrightarrow~~7+a+2+b = 9k~~\text{(adica multiplu de 9)} \\\\
\Longrightarrow~~\boxed{\overline{7a2b}\in \{7020;~7920;~7425\}}[/tex]