Explicație:
ms1= 50 g
c1=25%
c1= (md1/ms1)*100
md1= (c1*ms1)/100= 0,25*50= 12,5 g sare
ms2= 80 g
c2=75%
c2= (md2/ms2)*100
md2= (c2*ms2)/100= 0,75*80= 60 g sare
ms= ms1+ms2= 50+80= 130 g
md= md1+md2= 12,5+60= 72,5 g sare
c=(md/ms)*100= (72,5/130)*100= 55,77%