Mixed 300 g of 20% and 500 g of 40% salt solution. Find the salt concentration in the resulting solution.

The weight of the resulting solution will be equal to the sum of the masses of the two initial solutions.

M = 300 + 500 = 800 grams;

The mass of salt in the first solution is 300 x 0.2 = 60 grams;

The mass of salt in the second solution is 500 x 0.4 = 200 grams;

The mass of salt in the resulting solution will be 60 + 200 = 260 grams;

The salt concentration in the new solution will be 260/800 = 0.325 = 32.5%;