Thank you in advance for your kind help!

How much fresh water should be mixed to a 30% salt water solution, to obtain 90 gallons of a 23% salt water solution?

1 answer

you want to decrease the concentration by 23/30, so that means you have to increase the volume by 30/23.

30/23 x = 90
x = 90 * 23/30 = 69
So, add 21 gallons of water