Mixed 1 g of 55% salt solution and 2 g of 25% solution of the same salt. What is the new mass fraction of salt in the solution?

Let’s find the mass of the substance in the 1st solution:
m1 (v.-va) = mr.-pa1 (v.-va) * w1 (v.-va) / 100 = 1 * 55/100 = 0.55 (g).
Let’s find the mass of the substance in the 2nd solution:
m2 (v.-va) = mr.-ra2 (v.-va) * w2 (v.-va) / 100 = 2 * 25/100 = 0.5 (g).
Let’s find the mass of the substance in the new solution:
m3 (v.-va) = m1 (v.-va) + m2 (v.-va) = 0.55 + 0.5 = 1.05 (g).
Let’s find the mass of the new solution:
mr.-ra3 (v.-va) = mr.-ra1 (v.-va) + mr.-ra2 (v.-va) = 1 + 2 = 3 (g).
Let’s find the mass fraction of the substance in the new solution:
w3 (v.-va) = (m3 (v.-va) /mr.-pa3 (v.-va)) * 100 = (1.05 / 3) * 100 = 35 (%).