4l+3f=36 lei
5l+6f=50 lei
4l+3f+1l+3f=50 lei
36lei+1l+3f=50 lei
1l+3f=50-36=14 lei
1l+3f+3l=36 lei
14 lei+3l=36 lei
3l=36-14=22 lei
1l=22/3
22/3x5+6f=50
6f=50-110/3
6f=150/3-110/3=40/3
1f=40/3 :6=40/3x1/6=40/18
22/3x4+40/18x3=88/3+120/18=528/18+120/18=648/18=36=PROBA