Q:

Rahul purchased two different kinds of alcohol. In the first mixture the ratio of alcohol to water is 3:4 and in the second mixture it  is 5:6. If he mixes the two given mixture and makes a third mixture of 18 litres in which the ratio of alcohol to water is 4:5, the quantity of first mixture (whose ratio is 3:4) is required to make the 18 litres of the third kind of mixture is:

• 1
  5
• 2
  9
• 3
  6
• 4
  7