ms1 = 500 g , c1 = 20%
ms2 = 240 g , c2 = 40%
stim ca c = mdx100/ms
=> md1 = ms1xc1/100 = 500x20/100 = 100 g
md2 = 240x40/100 = 96 g
=> md.tot = 100 + 96 = 196 g
ms.fin = ms1 + ms2 + a , (a = masa de apa adaugata)
=> ms.fin = 740 + a
=> ms.fin = md.totx100/c.fin = 196x100/19,6
= 1000 g sol. finala
=> 1000 = 740 + a
=> a = 1000 - 740 = 260 g apa adaugata