Question 156804
let x=cm^3 of 15%, so 400-x=cm^3 of 6%


(15%)(x)+(6%)(400-x)=(9%)(400) __ multiply by 100 to clear percentages


15x+2400-6x=3600 __ subtracting 2400 __ 9x=1200 dividing by 9 __ x=400/3


substituting __ 400-(400/3)=800/3