An alloy of copper and zinc contains 45% copper and the rest is zinc. Find the weight of zinc in 20 kg of the alloy.
Total weight of alloy = 20 kg
Weight copper = 20 x 45% = 20 x 45/100 = 9 kg
Weight of zinc = (total weight of alloy – weight of copper) = 20 – 9 = 11 kg
