C= m,dx100/m,s unde m,s= m,d+m,apa
a. 20/100= m,d/180---..> m,d= 36g soda
b. 180g =m,d+m,apa---.> mapa=180-36= 144g apa; msoda/mapa=36/144=1/4
c. c2=md2 /1ms2----.> masa de soda se adauga si la md si la msol
C2=1,5x20=30%
30/100= md1+x/180+x calculeaza x,masa de sare adaugata
d. 15/100= 36./180+m,apa calculeaza m,apa adaugata