The solution contains 30% salt. If you add 120 g of salt, then the solution will contain 70% salt.

The solution contains 30% salt. If you add 120 g of salt, then the solution will contain 70% salt. What is the initial mass of the solution? How many grams of salt was in the solution initially?

Let us denote by the variable x the number of grams to which the mass of the initial solution corresponded.

Therefore, according to the condition of the problem, we can represent the mass of a possible new solution in the form (x + 120).

Knowing that a 70% solution will be obtained from a 30% original solution, we will draw up an equation and determine how many grams the mass of the original solution is equal to:

(30x + 120 * 100) / (x + 120) = 70;

40x = 120 * 100 – 120 * 70;

40x = 120 * 30;

x = 90.

Answer: The mass of the initial solution is 90 grams.