An alloy of copper and zinc weighs 5.2 kg, with zinc accounting for 30% of the weight of copper. How much copper is in this alloy.

Let’s say that this alloy contains x kg of copper.

Since the mass of zinc is 30% of the weight of copper, its amount will be: 0.3 * x kg.

We make an equation for the sum of the weight of copper and zinc.

Will be:

x + 0.3 * x = 5.2 kg.

1.3 * x = 5.2.

x = 5.2 / 1.3 = 4 kg of copper.

0.3 * x =, 3 * 4 = 1.2 kg of zinc.

Answer: There are 4 kilograms of copper in the alloy.