A zinc-copper alloy with 5 kg of pure zinc would contain 90% of zinc. The alloy with 3 kg of 90% zinc alloy contains 84% of zinc. Calculate the weight and percentage of zinc in the zinc-copper alloy.	Choose the correct choice.
A) 2.4 kg or 80%  B) 1.4 kg or 88%  C) 4.3 kg or 60%  D) 7.4 kg or 18%  E) 1.4 kg or 60%
Right Answer Explanation:   x : 5   y : 100   90   10 : 90 – y   (90-y)/5 = 10/x = ………..(1)   In the second case,   x 3   y 90   84   6 84-y   Therefore (84-y)/3 = 6/x ………..(2)   Dividing (1) and (2)   =   810 – 9y = 2100 – 25y   16y = 1290   y = 80.625   x = 50/(90-80.625) = 50/9.375 = 5.33 kg   Quantity of zinc in x = 80.625% of x   = 0.80625 5.33   = 4.3 kg   Weight and percentage of zinc is 4.3 kg or 80.625%   4.3 kg or 60%
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A zinc-copper alloy with 5 kg of pure zinc would contain 90% of zinc. The alloy with 3 kg of 90% zinc alloy contains 84% of zinc. Calculate the weight and percentage of zinc in the zinc-copper alloy.