SOLUTION: Fifty kilograms of a cement-sand mixture is 40% sand. How many kilograms of sand must be added for the resulting mixture to be 60% sand?

Question 159566: Fifty kilograms of a cement-sand mixture is 40% sand. How many kilograms of sand must be added for the resulting mixture to be 60% sand?
Answer by KnightOwlTutor(293) (Show Source): You can put this solution on YOUR website!
sand is 100%
Convert the percentages to decimal
100%=1
40%=.4
60%=.6
X=number of kilograms of sand
50(.4)+1(X)=(X+50)(.6)
The quantity hasn't changed only the percentage composition
Use the distributive property
20+X=.6X+30
Subtract .6 from both sides and subtract 20 from both sides
0.4X=10
X=25 kilograms of sand needed
Double check
50(.4)+25=75(.60)
45=45

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