5.5 ml of water and 14.5 g of the same salt were added to 85 g of a solution with a mass fraction

5.5 ml of water and 14.5 g of the same salt were added to 85 g of a solution with a mass fraction of potassium nitrate of 30%. The mass fraction of salt in the resulting solution is (in%)

The mass of potassium nitrate in the original solution.
m (KNO3) = W (KNO3) • m (solution) / 100% = 30% • 85 g / 100% = 25.5 g.
The mass of the substance in the resulting solution.
m (KNO3) = 25.5 g + 14.5 g = 40 g.
The mass of the solution after adding water and nitrate.
m (solution) = 85 g + 5.5 g + 14.5 = 105 g.
Mass fraction of potassium nitrate in solution.
W (KNO3) = m (KNO3) / m (solution) • 100% = 40 g / 105 g • 100% = 38%.