A piece of copper-tin alloy weighing 48 kg contains 40% copper. How much copper should you add

A piece of copper-tin alloy weighing 48 kg contains 40% copper. How much copper should you add to this piece to make an alloy containing 60% copper?

A 40% copper alloy weighing 48 kg contains copper:

48 * 40: 100 = 19.2 kg.

Suppose that in order to obtain 60% copper alloy, it is necessary to add x kg of copper to this alloy, then, according to the condition of the problem, we can compose the following equation:

(19.2 + x) / (48 + x) = 60/100,

19.2 * 100 + 100 * x = 48 * 60 + 60 * x,

2880 – 1920 = 100 * x – 60 * x,

40 * x = 960,

x = 960: 40,

x = 24 (kg) copper must be added to this alloy.

Answer: 24 kg.