md1=ms1xc1
md1=200x20/100=40g
masa apei ma=ms1-md1=200-40=160g
Se adauga x g apa .
md2=md1
ms2=ms1+x
c2=md2/ms2x100
10/100=40/ (200+x)
10x(200+x)=40x100
2000+10x=4000
10x=2000
x=200g -apa care se adauga