[tex]x=pretul\ initial\\
x+\frac{15x}{100}+\frac{20}{100}(x+\frac{15x}{100})=828\\
\frac{115x}{100}+\frac{2}{10}\cdot \frac{115x}{100}=828\\
\frac{115x}{100}+\frac{230x}{1000}=828 |\cdot 1000\\
1150x+230x=828000\\
1380x=828000\Rightarrow x=600 lei
[/tex]