c= mdx100/ms
=calculez md1---------------. > 25=md1x100/500----> md1=125g--> aceasta cantitate se gaseste si in a doua solutie md2=md1
c2=md2x100/ms2---> 50=125x100/ms2----> ms2=250g
m,apa evaporata= md1-md2= 500g=250g= 250g
=calculez md1
20/100= md1/400---> md1=80g
50= 80x100/ms2-----> ms2=160g
m,apa evaporata= ms1-ms2= 400g-160g= 240g
verifica, te rog, calculele !!!!