SOLUTION: how much of an alloy that 30% copper should be mixed with 300 ounces of an alloy that is 90% copper in order to get an alloy that is 40% copper ?

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Question 1057753: how much of an alloy that 30% copper should be mixed with 300 ounces of an alloy that is 90% 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% copper alloy needed
+%28+.3x+%2B+.9%2A%28+300+%29+%29+%2F+%28+x+%2B+300+%29++=+.4+
+%28+.3x+%2B+270+%29+%2F+%28+x+%2B+300+%29+=+.4+
+.3x+%2B+270+=+.4%2A%28+x+%2B+300+%29+
+.3x+%2B+270+=+.4x+%2B+120+
+.1x+=+150+
+x+=+1500+
1,500 ounces of 30% copper alloy are needed
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check:
+%28+.3x+%2B+.9%2A%28+300+%29+%29+%2F+%28+x+%2B+300+%29++=+.4+
+%28+.3%2A1500+%2B+.9%2A%28+300+%29+%29+%2F+%28+1500+%2B+300+%29++=+.4+
+%28+450+%2B+270+%29+%2F+1800+%29+=+.4+
+720+%2F+1800+=+.4+
+720+=+.4%2A1800+
+720+=+720+
OK