The glass contains 150 g of a 30% hydrochloric acid solution. what is the mass of acid in solution.

Knowing the formula for determining the mass fraction of a substance in a solution
W (in-va) = m (in-va) / m (solution) • 100%,
transform it to find the mass of acid in solution.
m (HCl) = W (HCl) • m (solution) / 100% = 30 • 150/100 = 45 g.
This means that for the preparation of 150 g of a 30% acid solution, it is necessary to take 45 g of the substance and (150 – 45) = 105 g of the solvent.