Question 855796: How many pounds of a 70% copper alloy must be melted with how many pounds of a 90% copper alloy to obtain 100 pounds of an 81% copper alloy? Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! Let = pounds of 70% alloy needed
Let = pounds of 90% alloy needed
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(1)
(2)
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(2)
(2)
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Multiply both sides of (1) by
and subtract (1) from (2)
(2)
(1)
and
(1)
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45 pounds of 70% alloy are needed
55 pounds of 90% alloy are needed
check:
(2)
(2)
(2)
(2)
OK
