Varianta 1.Presupunem ca toate ap.ar fi de 3 camere =>20*3=60 ap.;60-48=12 ap cu 2 camere ;20-12=8 ap.cu 3 camere.Proba:12*2+8*3=48.
Varianta 2. x+y=20;2x+3y=48;din prima relatie=>x=20-y,înlocuim in a doua relatie=>2 (20-y)+3y=48=>40-2y+3y=48;y=8 (ap.cu 3 camere)