c1=md1/ms1*100=>md1=ms1*c1/100=8*6/100=0,48 kg
md2=md1 pt ca nu se modifica cantitatea de dizolvat
ms2=md1+m apa adaugata
c2=md2/ms2*100=md1/(md1+m apa adaugata)*100=>5=0,48/(0,48+m apa adaugata)*100=>0,48*100=5(0,48+ m apa adaugata)=>48=5*0.48 + 5*m apa=>5*m apa=48-5*0,48=>5*m apa =45,6=>m apa adaugata = 9,12 kg!!!!