Răspuns:
notam:
a=2 camere
b=3 cam.
c=4 cam.
d=5 cam.
a+b+c+d=27 prima relatie
c=3d
b=2c-3=>b=6d-3
2a+3b+4c+5d=81 a2a relatie
inlocuim in prima relatie
a+6d-3+3d+d=27
a+10d=30=>a=30-10d
inlocuim in a2a relatie
2(30-10d)+3(6d-3)+4·3d+5d=81
60-20d+18d-9+12d+5d=81
15d=81-60+9
d=30:15
d=2 ap. cu 5 camere
c=3·2=6 ap. cu 4 camere
a=30-10·2=10 ap.cu 2 camere
b=6·2-3=9 ap.cu 3 camere
V:a+b+c+d=10+9+6+2=27 apartamente