How much water and salt is needed to make a 200 gram 15% mixture in a pharmacy.

Given:
m solution (salt) = 200 g
ω (salt) = 15%

To find:
m (salt) -?
m (H2O) -?

Decision:
1) Calculate the mass of salt in the solution, which will need to be taken to prepare the solution:
m (salt) = ω (salt) * m solution (salt) / 100% = 15% * 200/100% = 30 g;
2) Calculate the mass of water that will be needed to prepare the solution:
m (H2O) = m solution (salt) – m (salt) = 200 – 30 = 170 g.

Answer: The mass of salt is 30 g; water – 170 g.