1.
ms= 300g, c%= 40%
c% = mdx100/ms
=> md = msxc%/100 = 300x40/100 = 120g sare
2.
md= 200g, m.apa= 400g
ms = md+m.apa= 200+400 = 600g sol.
c%= mdx100/ms = 200x100/600 = 33,33%
3.
ms1= 200g, c1%= 30%
ms2= 300g, c2%= 10%
din c%
=> md1 = ms1xc1/100 = 200x30/100 = 60g
=> md2 = ms2xc2/100 = 300x10/100 = 30g
=> md.tot= md1+md2 = 60+30= 90 g
ms.tot= ms1+ms2 = 200+300 = 500 g
=> c%.final = md.totx100/ms.tot
= 90x100/500 = 18%
4.
md= 100g, c%= 30%
din c% => ms = mdx100/c%
= 100x100/30 = 333,33 g