To 200 g of a solution with a mass fraction of 10% salt was added 20 g of salt.

To 200 g of a solution with a mass fraction of 10% salt was added 20 g of salt. Calculate the mass fraction of salt in the resulting solution?

After adding a new portion of salt to the solution, its mass will become a wound of 200 + 20 = 220 grams.

The mass of salt in the initial solution is 200 x 0.1 = 20 grams.

In the new solution, the mass of salt will be 20 + 20 = 40 grams.

The mass fraction in the resulting solution will be 40/220 = 0.1818 = 18.18%;