Question

how much of an alloy that is 40% copper should be mixed with 400 ounces of an alloy that is 60% copper in order to get an alloy that is 50%

Answer 1

You have 400 ounces of 60% copper alloy.How many ounces of 40% must be added to make it 50%?
.60 * 400 + .40x = .50 * (400 + x)240 + .40x = 200 + .5x40 = .1xx = 400 ounces of 40% must be added.