a metalworker has a metal alloy that is 20% cooper and another alloy that is 55% copper. how many kilograms of each alloy should the metalworker combine to create 60kg of a 48% copper alloy?

Answer 1

.2x + .55(60-x) = .48(60) = 28.8

-.35x = 28.8 - 33 = -4.2

x = 4.2/.35 = 420/35 = 60/5 = 12 kg of 20% + 48 kg of 55% to get 60 kg of 48%

another approach:

55-48 = 7

48-20 = 28

28/7 =4 times as much 55% as 20%