The alloy of gold and silver has a mass of 2.5 kg. The mass of silver in it is 80% of the mass of the alloy.

The alloy of gold and silver has a mass of 2.5 kg. The mass of silver in it is 80% of the mass of the alloy. How much gold does the alloy contain?

In order to solve this problem and find out how much gold a given alloy contains, first we need to find the mass of silver in this alloy. To do this, you need to make up the proportion. Imagine the mass of silver as x.

2.5 kg – 100%;

x kg – 80%;

x = 2.5 * 80: 100 = 200: 100 = 2 kg;

Let’s find the mass of gold in the alloy:

2.5 – 2 = 0.5 kg, or 500 g;

Answer: the alloy contains 0.5 kg, or 500 g of gold.