[tex]x\to masa \ vasului \\ y\to masa \ apei \\\\ x+y=5kg \\\\ x+\frac{y}{2}=3kg \ 250g \\\\ 1kg\to1000g\\\\ 5kg\to 5000g \\\\ 3kg \ 250 g\to 3000g+250g=3250g\\\\\\ x=5000g-y \\\\ 5000g^{(2}-y^{(2}+\frac{y}{2}=3250g^{(2} \\\\ 10.000g-2y+y=6500g \\\\ 10.000g-y=6500g \\\\ 10.000g-6.500g=y \\\\ \boxed{y=3500g\to 3,5kg \ apa} \\\\ x=5kg-y \\\\ x=5kg-3,5kg \\\\ \boxed{x=1,5kg\ vasul}[/tex]
