Question 203260
I approached the problem in a different way and got a different answer,
but it seems to check out.
First,18oz. of salt in 36oz. of water is a 50% solution.
I don't think we need to be concerned with the amount of salt as a variable,
but only the amount of water we need to dilute our mixture down to a 24% concentration of salt.
If we let 'w' = water, then what we have is 18/36w = 0.05 (oop's, this is a typo. I mean 0.50) .
What we want is 18/w = 0.24, so...
 18/w = 0.24

 18 = 0.24w

 18/0.24 = w

 w = 75. So we need to have 18oz. of salt in 75 ounces of water to have a 24% solution.

To achieve this , we need to add 75oz. - 36oz. = 39oz. of water to our original mixture.

We check our answer by dividing 18oz.(salt)/75oz.(water)= 24%(salt).