[tex]c = \frac{md}{ms} \times 100[/tex]
[tex] = > \: md = \frac{c \times ms}{100} [/tex]
[tex]c1 = 15\% \: = > md1 = \frac{15 \times 400}{100} = 60 \: g[/tex]
[tex]c2 =25\% \: = > md2= \frac{25 \times 400}{100} = 100 \: g[/tex]
md=md1+md2=60+100=160 g
ms=ms1+ms2+200=400+400+200=1000 g
[tex]c = \frac{160}{1000} \times 100 = > c = 16\%[/tex]
