How much of an alloy with 30% copper must be added to 25 pounds of a second alloy which is 20% copper to create a 27% alloy?

If is the amount (by weight) of the first alloy that you will use, then the new alloy will have a total weight of .

The second alloy has 5 pounds of copper (20% of 25 = 5). 30% of the first alloy is copper, so that the amount of copper being introduced is , making the total amount of copper in the new alloy .

We want the proportion of copper in the new alloy to come out to 27% of the new alloy's weight, so that

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step-by-step explanation:

the solution is 12x-6y