The alloy contains 12 kg of copper, which is 4/19 of the mass of the entire alloy. What is the mass of the alloy?

We know that copper alloy contains 12 kg of copper. This is 4/19 of the mass of the entire alloy. In order to find what mass of copper alloy we will compose and solve the proportion.

We start by denoting the weight of the entire copper alloy as 1.

We introduce the variable x, denoting the weight of the copper alloy.

We now have enough data to compose the proportion.

12 kg of copper – 4/19;

x kg of alloy – 1.

We get the proportion.

12 / x = (4/19) / 1;

Let’s apply the main property of proportion and get:

4 / 19x = 12 * 1;

4 / 19x = 12;

x = 12 * 19/4;

x = 57 kg copper alloy weight.