Răspuns:
utilizez relatia
c=mdx100/ms, unde ms=md+m,apa
solutia 1
ms1=500g
c1=10%
md1= c1xms1/100= 10x500/100g= 50g sare
in a doua solutie, prin adaugare de sare, se modifica si md si ms
c2=25%
md2=md1+md=50+md
ms2=ms1+md= 500+md
25/100= (50+md)/ (500+md)
25(500+md)=100(50+md)----> md= 100g sare
Explicație: