In 90 liters mixture of milk and water, the ratio of the amount of milk to that of the amount of water is 5 ∶ 4. In order to make this ratio 1 ∶ 1. How many liters of water should be added?

10

In 90 litres

Quantity of milk = 90 × (\(\frac{5}{9}\)) = 50 liters

Quantity of water = 90 × (\(\frac{4}{9}\)) = 40 liters 

Let x liters of water is added in the mixture to make the ratio of milk to water 1 ∶ 1

⇒ (\(\frac{50}{40 + x}\)) = \(\frac{1}{1}\)

⇒ 50 = 40 + x

⇒ x = 50 - 40 = 10