Question

How much water must be added to 80 liters of 60% alcohol solution in order to get 35% alcohol solution ?

Answer 1

Calculate the number of litres of alcohol first.
60% of 80 litres= 0.6*80= 48 liters.

To get a 35% alcohol solution, that means 48 liters is 35% of the total volume of the solution.

Since 48 is the 35% find 100%,
48/35 * 100= 137liters.

How much water must be added?
137 - 80 = 57 liters.