As a result of mixing 25% and 15% sulfuric acid solutions, 750 g of a 20% solution

As a result of mixing 25% and 15% sulfuric acid solutions, 750 g of a 20% solution were obtained. How many grams of a 15% solution was taken?

Let the mass of a 15% solution be x g, then the mass of a 25% solution is (750-x) g.

Based on this, we get an equation of the form:

0.15x + 0.25 * (750 – x) = 0.2 * 750;

0.15x + 0.25 * 750 – 0.25x = 0.2 * 750;

0.15x + 187.5 – 0.25x = 150;

-0.1x = -37.5;

x = 375.

Answer: the mass of a 15% solution is 375 g.