solutia 1
c1=20%
ro=1,4g/cmcub= > ms1= 1,4 x Vs1
c=md1x100/ms1
20/100= md1/1,4xVs1---> md1= 20x1,4xVs1/100 g
aceeasi masa de acid se gaseste si in solutia 2-> md2=md1
solutia 2
md2=md1= 0,2x1,4xVs1
md2/mapa=1/7 ---> m,apa= 7md2
ms2=140g=md2+m,apa= md2+ 7md2= 8md2
140= 8x0,2x1,4xVs1 ---> Vs1= ...................calculeaza !!!