Mixed 80 g of a solution with a mass fraction of sodium nitrate 25% and 20 g

Mixed 80 g of a solution with a mass fraction of sodium nitrate 25% and 20 g of a solution of the same salt with a moss fraction of 40%. Mass fraction of salt in the resulting solution is

Given:
m1 solution (NaNO3) = 80 g
ω1 (NaNO3) = 25%
m2 solution (NaNO3) = 20 g
ω2 (NaNO3) = 40%

To find:
ω3 (NaNO3) -?

Decision:
1) m1 (NaNO3) = ω1 (NaNO3) * m1 solution (NaNO3) / 100% = 25% * 80/100% = 20 g;
2) m2 (NaNO3) = ω2 (NaNO3) * m2 solution (NaNO3) / 100% = 40% * 20/100% = 8 g;
3) m3 (NaNO3) = m1 (NaNO3) + m2 (NaNO3) = 20 + 8 = 28 g;
4) m3 solution (NaNO3) = m1 solution (NaNO3) + m2 solution (NaNO3) = 80 + 20 = 100 g;
5) ω3 (NaNO3) = m3 (NaNO3) * 100% / m3 solution (NaNO3) = 28 * 100% / 100 = 28%.

Answer: The mass of NaNO3 is 28%.