x=apartamente cu 2 camere
y=aparatamente cu 4 camere
[tex] \left \{ {{x+y=45} \atop {2x+4y=140}} \right.\ \textless \ =\ \textgreater \ \left \{ {{4x+4y=180} \atop {2x+4y=140}} \right.\\
Le\ scadem :2x/=40=\ \textgreater \ x=20\ apartamente\ cu\ 2\ camere\\
x+y=45\\
20+y=45=\ \textgreater \ y=25\ apartamente\ cu\ 4\ camere\
[/tex]