So you start out with 6 pints of 60% salt and 40% water. That means you start out with 60% salt mixture (duh). As you add one pint of water, the mixture becomes 6 pints of 60% salt and 1 pint of 100% water changing the mixture to 7 pints of solutions with around 0.52% salt and about 8% less salt. This can be found through averaging the 6 pints of 60% salt (also know as 6 pints 40% water) and the 1 pint of (100%) water: \(x = {{(0.40)+(0.40)+(0.40)+(0.40)+(0.40)+(0.40)+(1.00)} \over 7}\).
This x value gets the percentage of water of the new liquid, (This is due to changing the salt mixture percentages, of 60% into water mixture percentages, of 40%, to be able to average the liquids). Subtract 100 by the x value and you get the percentage of salt in the solvant, 52%.
** The (0.40) values are the amount of water percentage in a pint of 60% salt.
After this you keep adding pints of water and calucalting to get get closer to a mixture which is 36% salt (which is 24% less the origninal 6 pints 60% salt mixture.)
Maybe Answer: If 1 pint of water made the mixture 8% less salt to 52% salt than 3 pints of water would most likely make the mixture 36% salt.