md1=45g zahar
C%=15%
in 100g sol. avem 15g zahar si 85g apa
daca 15g zahar........85g apa
45g zahar.......xg apa
x=45x85:15=225g apa
apa evaporata o notam cu y
C%2=30%
in 100g sol. avem 30g zahar si 70g apa
md2=md1=45g zahar
ma2=ma1-y=225-y
daca 30g zahar........70g apa
45g zahar........225-y
225-y=45x70:30=105
y=225-105=120 g apa de evaporat