[tex]\displaystyle\bf\\\overline{ab0} + \overline{ab41} =2021\\\\\overline{ab0} + \overline{ab00}+41 =2021\\\\\overline{ab0} + \overline{ab00} =2021-41\\\\\overline{ab0} + \overline{ab00} =1980\\\\10\cdot\overline{ab} + 100\cdot\overline{ab} =1980\\\\~~~~~~~~~~~~~~\boxed{\bf\overline{ab}=x}~~(substitutie)\\\\10x + 100x =1980\\\\110x=1980\\\\x=\frac{1980}{110}\\\\\boxed{\bf x=18}\\\\~~~~~~~~~~~~~Ne~intoarcem~la~substitutie.\\\\\overline{ab}=x=18\\\\\implies~\boxed{\boxed{\bf\overline{ab}=18}}\\\\[/tex]
