[tex]x\to pretul \ initial \\\\ 25\% \ din \ x =\frac{25}{100}*x= \frac{1}{4}*x \to \frac{x}{4}-reducerea \\\\ x^{(4}-\frac{x}{4}=\frac{4x-x}{4}=\frac{3x}{4}-noul \ pret \\\\ 20\% \ din \ \frac{3x}{4}=\frac{20}{100}*\frac{3x}{4}=\frac{1}{5}*\frac{3x}{4}\to \frac{3x}{20}-marirea \\\\ \frac{3x}{4}^{(5} +\frac{3x}{20} =\frac{15x+3x}{20}= \frac{18x}{20}\to \frac{9x}{10}-noul \ nou \ pret \\\\ \frac{9x}{10}=3600 \\\\ x=\frac{10*3600}{9} \\\\ x=10*400 \\\\ \boxed{x=4000}[/tex]
