SOLUTION: An alloy of copper and iron weighs 60 gms. It contains 70 percent copper. How much copper should be added so that the new alloy formed contains 85 percent copper?

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Question 764593: An alloy of copper and iron weighs 60 gms. It contains 70 percent copper. How much copper
should be added so that the new alloy formed contains 85 percent copper?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
{amount of pure copper}/{amount of alloy}={percent copper}

You want to add g grams of copper which will both increase the amount of copper AND increase the amount of alloy.

{amount of pure copper originally + g}/{amount of alloy originally + g}={new percent copper}

%2860%2A0.70%2Bg%29%2F%2860%2Bg%29=85
Solve for g.