SOLUTION: How much of an alloy that is 10% copper should be mixed with 400 ounce of an alloy that is 90% copper in order to get an alloy that is 30% copper

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Question 1020061: How much of an alloy that is 10% copper should be mixed with 400 ounce of an alloy that is 90% copper in order to get an alloy that is 30% copper
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = ounces of 10% alloy needed
+.1x+ = ounces of copper in 10% alloy
+.9%2A400+=+360+ = ounces of copper in 90% alloy
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+%28+.1x+%2B+360+%29+%2F+%28+x+%2B+400+%29+=+.3+
+.1x+%2B+360+=+.3%2A%28+x+%2B+400+%29+
+.1x+%2B+360+=+.3x+%2B+120+
+.2x+=+240+
+x+=+1200+
1200 ounces of 10% alloy is needed
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check:
+%28+.1x+%2B+360+%29+%2F+%28+x+%2B+400+%29+=+.3+
+%28+.1%2A1200+%2B+360+%29+%2F+%28+1200+%2B+400+%29+=+.3+
+%28+120+%2B+360+%29+%2F+1600+=+.3+
+480+%2F+1600+=+.3+
+480+=+.3%2A1600+
+480+=+480+
OK