A juice seller mixes 30 litres of juice costing ₹80 a litre with 10 litres of water, which costs nothing. What does a litre of the mixture cost him?

Explanation

1. 01

   All the cost is in the juice: $30 \times 80 = 2{,}400$ rupees, spread over 40 litres.

2. 02

   $\frac{2{,}400}{40} = 60$ rupees a litre.