Mixed 80 g of a solution by mass fraction of sodium nitrate 10% and 120 g of a solution of the same salt with

Mixed 80 g of a solution by mass fraction of sodium nitrate 10% and 120 g of a solution of the same salt with a mass fraction of 25%. The mass fraction of salt in the resulting solution is equal to ..

Given:
m1 solution (NaNO3) = 80 g
ω1 (NaNO3) = 10%
m2 solution (NaNO3) = 120 g
ω2 (NaNO3) = 25%

To find:
ω3 (NaNO3) -?

Decision:
1) m1 (NaNO3) = ω1 (NaNO3) * m1 solution (NaNO3) / 100% = 10% * 80/100% = 8 g;
2) m2 (NaNO3) = ω2 (NaNO3) * m2 solution (NaNO3) / 100% = 25% * 120/100% = 30 g;
3) m3 (NaNO3) = m1 (NaNO3) + m2 (NaNO3) = 8 + 30 = 38 g;
4) m3 solution (NaNO3) = m1 solution (NaNO3) + m2 solution (NaNO3) = 80 + 120 = 200 g;
5) ω3 (NaNO3) = m3 (NaNO3) * 100% / m3 solution (NaNO3) = 38 * 100% / 200 = 19%.

Answer: The mass of NaNO3 is 19%.