SOLUTION: How much of an alloy that is 30% copper should be mixed with 600 ounces of an alloy that is 60% copper in order to get an alloy that is 40% copper?

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Question 774957: How much of an alloy that is 30% copper should be mixed with 600 ounces of an alloy that is 60% copper in order to get an alloy that is 40% copper?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = ounces of 30% alloy needed
+.3x+ = ounces of copper in 30% alloy
+.6%2A600+=+360+ ounces of copper in 60% alloy
------------------
+%28+.3x+%2B+360+%29+%2F+%28+x+%2B+600+%29+=+.4+
+.3x+%2B+360+=+.4%2A%28+x+%2B+600+%29+
+.3x+%2B+360+=+.4x+%2B+240+
+.1x+=+360+-+240+
+.1x+=+120+
+x+=+1200+
1200 ounces of 30% alloy are needed
check:
+%28+.3x+%2B+360+%29+%2F+%28+x+%2B+600+%29+=+.4+
+%28+.3%2A1200+%2B+360+%29+%2F+%28+1200+%2B+600+%29+=+.4+
+%28+360+%2B+360+%29+%2F+1800+=+.4+
+720+=+.4%2A1800+
+720+=+720+
OK