amount of 25% copper needed ---- x kg
amount of 55% copper needed = 90-x kg
.25x + .55(90-x) = .49(90)
solve for x
A metalworker has a metal alloy that is 25% copper and another alloy that is 55% copper. How many kilograms of each alloy should the metalworker combine to create 90 kg of a 49% copper alloy?
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