6.
ms= 200g , c%= 5%
stim ca c% = mdx100/ms
=> md = msxc%/100 = 200x5/100 = 10 g
7.
notam cu a = masa de apa evaporata
ms1 = 380 g , c1%= 20%
c.f.% = 60%
md = ms1xc1/100 = 380x20/100 = 76 g
ms.final = ms1-a = 380-a
=> 60 = 76x100/(380-a)
=> a = 15200/60 = 253,33 g
