<PRE><B>Question 818621</B>
a = weight of 30% copper allow
w = weight of final mixture
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30a + 70(100) = 50w
w = 100 + a
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30a + 7000 = 50w
30a + 7000 = 50(100 + a)
30a + 7000 = 5000 + 50a
20a = 2000
a = 100
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answer:
mix in 100 ounces of 30% copper alloy
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