putem aplica regula dreptunghiului (metoda grafica)
c1%= a -------------------> c.f.-c2%= 16-0 = 16 parti masa c1%
c.f.%= 16%
c2%= 0 (apa) ----------> c1%-c.f.= a-16 parti masa sol. c2%
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total = 16+a-16 = a parti sol. finala c.f.%
a parti sol.finala ................. 16 parti sol c1 ......... a-16 parti apa
ms ..................................... 400 g .......................... 150 g apa
=> a-16 = 150x16/400 = 6 => a = 22%
metoda algebrica
ms1 = 400 g, c1% = a
m.apa = 150 g
c2% = 16
16 = mdx100/ms.final
16 = mdx100/400+150
=> md = 16x550/100 = 88 g
=> c1% = mdx100/ms1
= 88x100/400 = 22%
