se poate rezolva cu regula dreptunchiului , ca in caiet, dar si prin calacule
c= mdx100/ms
c3= md3x100/.ms3
md3= md1+md2= c1xms1/100+c2xms2/100
ms3=ms1+ ms2
40= (25xms1+35xms2)/(ms1+ms2)
40ms1+40ms2= 25ms1+35ms2
15ms1=5ms2---> ms1/ms2= 5/15= 1/3
dar ms1+ ms2= 400---> ms1=100g ms2=300g