Question

In seawater there is 5% of salt. How many liters of fresh water do you need to add to 30 liters of seawater to get a 1.5% solution of salt?

Answer 1

Let x = amout of fresh water required
The amount of the salt remains the same
.05(30) = .015(x+30)
1.5 = .015x + .45

1.5 - .45 = .015x
1.05 = .015x
x = 1.05/.015
x = 70 liters of fresh water

check solution
.05(30) = .015(100)
1.5 = 1.5