A metal alloy is 25% copper. Another metal alloy is 50% copper. How many grams of the 50% copper alloy should be used to make 1000 grams of a metal alloy that is 45% copper?
Well if the alloy makes the 1000 grams, but you are dealing with copper that isn't even 100% copper, than you either need 55% more copper, which isn't given, which means you really need 550 grams of alloy copper.
