Calculate what masses of anhydrous sodium carbonate and water you need to take to prepare a solution

Calculate what masses of anhydrous sodium carbonate and water you need to take to prepare a solution weighing 60 g with a mass fraction of 15%

The mass of the solution m (solution) consists of the mass of the solvent (water) m (H2O) and the mass of the solute (Na2CO3) m (Na2CO3):
m (p-pa) = m (Na2CO3) + m (H2O)
Mass fraction of solute w = m (Na2CO3) / m (p-pa), from here we express m (Na2CO3) = w * m (p-pa) = 0.15 * 60 = 9 g.
Find the mass of water: m (H2O) = m (p-pa) – m (Na2CO3) = 60 – 9 = 51 g.