To 200 g of a 40% salt solution was added 300 g of water. What is the concentration of the salt solution?

1) 40%: 100% = 0.4 (part) of the original solution is salt.

2) 200 * 0.4 = 80 (g) salt.

3) 200 – 80 = 120 (g) of water was in the original solution.

4) 120 + 300 = 420 (g) of water became in the new solution.

5) 420 + 80 = 500 (g) weight of the new solution.

The weight of the new solution is 500 g, and of which 80 g is the weight of the salt. Means:

6) 80: 500 = 0.16 (part) of the whole new solution is salt.

7) 0.16 * 100% = 16 (%) concentration of the new solution (that is, of the whole new solution is salt).