trebuie sa aflam aria totala in cm^{2} L=1,2m=120cm, l=0,5 m=50cm
At=Al+2Ab
Al=2(Lxh+lxh)=2(120x30+50x30)=2(3600+1500)=2x5100=10200cm^{2}
Ab=Lxl=120x50=6000cm^{2}
At=10200+2x6000=10200+12000=22200cm^{2}
100cm^{2} ..................3g
22200cm^{2} ..............xg
x=22200*3/100=222*3=666 g de vopsea
