Răspuns:
ms1=30g
C1=5%
ms2=20g
C2=20%
C3=?
md1=C1×ms1/100=5×30/100=1,5g
md2=C2×ms2/100=20×20/100=4g
md3=md1+md2=1,5+4=5,5g
ms3=ms1+ms2=30+20=50g
C3=md3×100/ms3=5,5×100/50=11%
