Please, I need your help!How much water must be evaporated from 16oz of a 2% salt solution to make a 4% salt solution?

Answer 1

twice the concentration means half the volume, since the same amount of salt remains.

So, we lost half of 16 oz, or ?

Answer 2

by intuition, it must be 8 oz

or

the amount of salt must stay the same, so
.02(16) = .04(16-x)
.32 = .64 - .04x
.04x = -.32
x = 8

Answer 3

How much water must be evaporated from 260 gallons of 5% salt solution to produce an 8% salt
solution?