What is the concentration in mass percent of a solution prepared from 50.0g nacl and 150.0g of water?

M (NaCl) = 50.0 g

m (H₂O) = 150.0 g

m (solution) = m (NaCl) + m (H₂O)

w (NaCl) = 100m (NaCl) / m (solution) = 100m (NaCl) / {m (NaCl) + m (H₂O) }

w (NaCl) = 100*50.0 / (50.0+150.0) = 25%