s=pret/metru sarma, c=pret/metru cablu, t=pret/metru tub
32s+40c+25t=1784
t=2s, s=t/2
t=6c/5, c=5t/6, inlocuim s si c in prima relatie
32*t/2+40*5*t/6+25t=1784, numitor comun 6
96t+200t+150t=10704, 446t=10704, t=10704/446=24lei
s=24/2=12lei, c=24*5/6=120/6=20lei