Cyclic Transfer of Brine (Salty Water)

Three beakers of the same size are filled each with $500$ mL of three brine solutions with different concentrations. The first beaker has pure water (salt concentration is $0$ g / L ). Second beaker brine has a salt concentration of $100$ g / L , while the third beaker has a salt concentration of $20$ g / L. Now, $200$ mL is transferred from the first beaker to the second beaker, and the second beaker is shaken well, then $200$ mL is transferred from the second beaker to the third beaker, and the third beaker is shaken well, and finally, $200$ mL is transferred from the third beaker to the first beaker, and the first beaker is shaken well. This whole sequence of three transfers is repeated two more times. At the end, what will be the difference in g/L between the highest concentration of salt in a beaker and the lowest concentration ?