A milk vendor has 2 vessels of milk and water. The first contains 80% milk and the rest is water. The second contains 50% milk. How much mixture (in L) should he mix from each of the vessels so as to get 9 litres of mixture such that the ratio of water to milk is 1: 2? (Write your answer in the order of vessel 1 and vessel 2)

Correct option is D

Let's denote the volume of milk to be taken from the first can by 'x' litres and from the second can by 'y' litres.
=> x+y = 9 ..................(1)
In the first can, the milk portion is 80% and in the second can, it's 50%.
The new mixture should have a milk percentage of 66.66% (since the water: milk ratio is 1:2, the milk percentage becomes 2/(1+2) = 66,66%.
=> (80x + 50y) / 9 = 66.666%
=> 80x + 50y = 600... (2)
Solve equation (1) and (2) we get x= 5 and y = 4