Notam x= creioane si y= caiete; si obtinem 3x+5y=57500; 4x+2y=30000; adunam cele doua relatii si obtinem 7x+7y=87500=> 7(x+y)=87500 => x+y=87500:7= 12500; x+y=12500=> x=12500-y inlocuim in prima rel si obtinem 3(12500-y)+5 y=57500; 37500-3y+5y=57500; 2y=57500-37500; y=20000:2; y=10000 => x=12500-10000; x=2500