Răspuns :

m.apa = 200g

ms1 = 800g , c1% = 40%

stim ca:

ms.final = ms1 + m.apa = 1000 g

c% = mdx100/ms

=> md = ms1xc1%/100

= 200x40/100 = 80 g

=> c%final = mdx100/ms.finala

= 80x100/1000 = 8%