To 150 g of a 5% sodium chloride solution was added 5 g of the same salt. What is the mass fraction

To 150 g of a 5% sodium chloride solution was added 5 g of the same salt. What is the mass fraction of salt in the new solution?

The mass of salt in the original solution.
m (salt) = W (salt) • m (solution) / 100% = 5% • 150 g / 100% = 7.5 g.
Total mass of salt.
m (salt) = 7.5 g + 5 g = 12.5 g.
The mass of the solution after adding salt.
m (solution) = 150 g + 5 g = 155 g.
Mass fraction of salt in the resulting solution.
W (salt) = m (salt) / m (solution) • 100% = 12.5 g / 155 g • 100% = 8%.