In a mixture of 60 litres, the ratio of milk and water is

In a mixture of 60 litres, the ratio of milk and water is 2 : 1. How much more water must be added to make its ratio 1 : 2 ?

In original mixture,
Milk = 40 litres
Water = 20 litres
If x litres of water is mixed,

40	=	1
20 + x	=	2

⇒ 20 + x = 80
⇒ x = 60 litres