300 g of 25% solution contains solute = 75g

400g of 40% solution contains solute = 160 g

Total mass of solute = 160 + 75 = 235 g

Total mass oÍ’ solution = 300 + 400 = 700 g

% of solute in the final solution = \(\frac{235}{700}\) x 100 = 33.5%

% of water in the finaI solution = 100 – 33.5 = 66.5%