A milkman mixes 20 litres of milk costing ₹60 a litre with 5 litres of water, which costs him nothing. What does a litre of the mixture cost him?

Explanation

1. 01

   The cost is all in the milk: $20 \times 60 = 1{,}200$ rupees, now spread over 25 litres.

2. 02

   $\frac{1{,}200}{25} = 48$ rupees a litre.