1) cp=md/ms *100
cp-concentratia procentuala
md-masa substantei dizolvate
ms-masa solutiei
ms=md + m H2O
3,6l= 3,6kg= 3600g
cp= 400/(400+3600) *100
cp= 400/4000 *100
cp=400/40
cp=10%
2)-1 +2 -3 + 4-5+.....-199+200=
= -1 -1-1.....-1 } de 100 ori
= -1*100= -100
