How much calcium nitrate and water do you need to take to prepare 160 grams of a solution with a mass fraction of a solute of 15%?

Given:
m solution (Ca (NO3) 2) = 160 g
ω (Ca (NO3) 2) = 15%

To find:
m (Ca (NO3) 2) -?
m (H2O) -?

Decision:
1) Calculate the mass of calcium nitrate in the solution, which will need to be taken to prepare the solution:
m (Ca (NO3) 2) = ω (Ca (NO3) 2) * m solution (Ca (NO3) 2) / 100% = 15% * 160/100% = 24 g;
2) Calculate the mass of water that will be needed to prepare the solution:
m (H2O) = m solution (Ca (NO3) 2) – m (Ca (NO3) 2) = 160 – 24 = 136 g.

Answer: The mass of calcium nitrate is 24 g; water – 136 g.