To 500 g of a 22% solution of the substance, 300 g of a 30% solution

To 500 g of a 22% solution of the substance, 300 g of a 30% solution of this substance was added. What is the concentration of the resulting mixture?

Let us determine to what number of grams the mass of the resulting solution corresponds, knowing by the condition of the problem that the first solution was taken to prepare a mixture of 500 grams, and the second solution was 300 grams:

500 + 300 = 800.

Let us determine the concentration of the resulting solution, knowing by the condition of the problem that the concentration of the first solution was 22%, the concentration of the second solution was 30%:

(22 * 500 + 30 * 300) / 800 = (11000 + 9000) / 800 = 20,000 / 800 = 25.

Answer: The concentration of the resulting solution is 25%.