o sa notez asa: msi= masa solutie initiala
mdi= masa dizolvat initial
c= concentratie
msf=masa solutie finala.....
msi=500 g
c=25%
mdi=msi*c/100=500*25/100=125g
msf=msi+masa apa=500+300=800g
mdf=mdi=125g
c=mdf/msf*100=12500/800=125/8=15,625%
Sper ca am fost de ajutor! :)