The solution contains 40% salt, if you add 120 g of salt, then the solution will contain 70% salt

The solution contains 40% salt, if you add 120 g of salt, then the solution will contain 70% salt, how many grams of salt was in the solution initially.

1. Let the solution contain x kg of salt. Therefore, the mass of the entire solution was x / 0.4 = (10 * x) / 4 = (5 * x) / 2 kg.

After adding 120 g of salt, the solution became 120 + x kg.

The mass of the solution after addition was (5 * x) / 2 + 120 kg.

Let’s make the equation:

(120 + x) / ((5 * x) / 2 + 120) = 0.7;

120 + x = (3.5 * x) / 2 + 84;

120 + x = 1.75 * x + 84;

0.75 * x = 36;

3/4 * x = 36;

x = 36 * 4/3;

x = 12 * 4;

x = 48.

Answer: there were 48 kg of salt.