Question 1124664
Suppose total volume of solution is 1 liter
water volume is 0.8 liters, salt is 0.2 l 
remove 25% of water and remove 0.2 l so 0.6 l of water is left. This has the same 0.2 salt.  Total volume is now 0.8 liters of which 0.2 is salt.
25% or 1/4.