Neha has 30 litres of a 20% salt solution. How much water must she add to bring the salt concentration down to 12%?

Explanation

1. 01

   Salt = $0.20 \times 30 = 6$ litres, and adding water does not change it.

2. 02

   For 6 litres to be 12%, the total must be $\frac{6}{0.12} = 50$ litres.

3. 03

   Water to add = $50 - 30 = 20$ litres.