To find the mass of water (h20) in the solution, we can first calculate the mass of the solute (Mр-ра) and then use the information provided about the water content (w=20%).

Given:
Mр-ра = 300g
w = 20%

Calculate the mass of the solute (Mр-ра):
Mр-ра = 300g

Calculate the mass of water (h20) using the water content (w=20%):
Mass of water (h20) = 300g x 0.20 = 60g

Therefore, the mass of water in the solution is 60g.