ms3=400
c3=20%
ms1=x
c1=5%-----------------------> md1= c1xms1/100
ms2=y
c2= 25%----------------------> md2=c2xms2/100
c3= md3x100/ms3= (md1+md2)100/(ms1+ms2)
20= (0,05xms1+0,25xms2)/ (ms1+ms2)
ai un sistem de 2 ecuatii
x+y=400
20=(0,05x+0,25y)./ 400 rezolva sistemul !!!!