1. Impartim rapoartele la masele atomice
Na: 43,39/23=1,8865
C: 11,32/12=0,9433
O: 45,28/16=2,83
2. Le impartim la raportul cel mai mic, obtinand raportul atomic
Na: 1,8865/0,9433=2
C: 0,9433/0,9433=1
O: 2,83/0,9433=3
Na:C:O=2:1:3 => Na2CO3
raportul masic: Na:C:O=46:12:48=23:6:24
80/100=mpur/270 =>mpur=270*0,8=216g
MNa2CO3=46+12+48=106g
106g.......46gNa
216.........x=? => x=216*46/106=93,73g Na