200 g of a 30% salt solution was boiled, resulting in a solution weighing 180 g.

200 g of a 30% salt solution was boiled, resulting in a solution weighing 180 g. Determine the mass fraction of salt in the resulting solution.

Progress in solving the problem:
1) Calculation of the mass of the solute in the solution. To do this, we multiply the mass fraction of the substance by the mass of the solution and divide by one hundred percent.
2) Calculation of the mass fraction of the substance in the resulting solution. For this, the mass of the solute is divided by the mass of the solution and multiplied by one hundred percent.
Solution:
1) 200 * 30/100 = 60g.
2) 60/180 * 100 = 33.3% – the answer.