An alloy contains only zinc and copper and they are in the ratio of 7:9. If the weight of the alloy is 8kg, then find the weight of copper in the alloy.

Let the weight of zinc and copper in the alloy be the 7x and 9x

Weight of the alloy = 8 kg

Total weight = 7x+9x = 16x

16x = 8

Weight of copper = 9× = 4.5 kg

Hence, weight of the copper in alloy 4.5 kg.