ms=300g
c=10%
ms2=400
c2=40%
mapa=200g
----------------
c=?
ms3=ms1+ms2
ms3=300+400
Ms3=700g
md1=ms1xc1/100
md1=300x10/10
md1=3000/100
md1=30g
md2=ms2xc2/100
md2=400x40/100
md2=4x40
md2=160g
md3=md1+md2
md3=30+160
md3=190g
c3=md3/ms3x100
c3=190/700x100
c3=19/70x100
c3=1900/70
c3=2.714% rex final