se amesteca cele doua solutii si se formeaza o a treia solutie
ms1=200g ms2=500g ms3=ms1+ms2=700g
c1=30% c2=50% c3=?
md1=ms1*c1/100=200*30/100
=60g
md2=ms2*c2/100=250g
md3=ms3*c3/100 =700*c3/100 (1)
dar md3=md1+md2=60+250=310g (2) se egaleaza (1) cu (2) Si c3=44,28%