Prin evaporare de apa md ramane neschimbat si vom avea o noua masa solutie (adica alt ms)
ms1 = 600 g
c%1 = 20%, c% = mdx100/ms
=> md = ms1xc%1/100 = 600x20/100 = 120 g
=> c2% = 40% (deupa evaporare)
=> ms2 = mdx100/c%2 = 120x100/40 = 300 g sol. finala
=> m.apa evaporata = ms1 - ms2 = 600 - 300 = 300 g
